# Position, Velocity, and Acceleration

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 Chapter 2 Position, Velocity, and Acceleration In this section, we will define the first set of quantities (position, velocity, and acceleration) that will form a foundation for most of what we do in this course. 2.1 Definition: Position Position simply refers to the location of an object. For example, consider a bumble bee flying around a room. At any instant, you can mathematically define the location or position of the bee with a set of three numbers which we define as x, y, andz. We can define x as the distance of the bee from the south wall of the room; y as the distance of the bee from the east wall of the room; and z as the height or distance above the floor. W S N E B z y x Figure 2.1: The position of a bee (point B) can be specified by three distances: x, y, andz Position as a Vector Because we need three numbers to specify position, we can think of position as a vector: = x î + y ĵ + z r ˆk, (2.1) 2

2 where x, y, andz are the components of position in the î, ĵ, andˆk directions. By now, you should be quite familiar with the concept of a vector. If it s fuzzy, I urge you to look at the Appendix on Review of Vectors. Graphically, a position vector looks like that shown in Figure 2.2. Recall that a vector is something that has both magnitude and direction. Theposition vector s magnitude (length of the vector) is r = x 2 + y 2 + z 2. (2.2) This is the distance of the bee from the origin of our coordinate system. The direction of the position vector is the direction of the bee as viewed from the origin of the coordinate system. z k r B yj xi Figure 2.2: The position vector, r Reduced Dimensions Instead of being interested in a bee flying around a room, suppose that we are interested in a spider crawling on the floor. In this case, the spider s position can be written as r = x î + y ĵ +0ˆk. (2.3) Here, the floor is defined as z 0, so the last term in the sum does not provide any important information and we can write r = x î + y ĵ. (2.4) Here we say that the dynamics of the spider is two dimensional (2D), since is position can be described by only two coordinates: x, andy (assuming the spider doesn t begin climbing up any walls). One dimensional (1D) dynamics are also possible. You can think of a train car traveling on a long straight segment of railroad track. In this case, one could write the velocity vector as assuming the î direction is in the direction of the track. r = x î, (2.5) 3

3 2.1.3 Position Has Units of Length In mechanics all quantities have units of mass, length, time, or some combination of the three. Recall that, in our position vector of Equation (2.1), the symbols x, y, andz represented distances of the bee from different reference planes. Distances are lengths. Thus position has units of length. It is very important that you know this. 2.2 Definition: Velocity I suspect that you already have some notion of what velocity is. As you re driving your car, you may look down at the speedometer and observe that you re traveling at a rate of 60 miles per hour. That 60 mph is your velocity, right? Well, kind of. In this section we re going to carefully define what velocity is. In mechanics, we define velocity as follows: Velocity is the time derivative of the position vector. Sounds simple, eh? If your understanding of time derivative is a bit fuzzy, I urge you to read the brief review in Appendix B.1. Our definition of velocity is a little trickier than the derivatives in the appendix because here we re taking the derivative of a vector. As we re developing our understanding of velocity, I will refer to the picture in Figure 2.3(a). We can think of an ant walking along the path shown. At time t = t 0, we denote the position vector of the ant to be r (t 0 ). x r ( t 0 ) r ( t 1 ) x x path r ( t 1 ) r ( t 0 ) v( t ) 0 r ( t 0 ) r ( t 0 ) r ( t 1 ) (a) (b) (c) y y y Figure 2.3: Definition of velocity. The time derivative of the position vector at t 0 is given by ṽ(t 0 )= dr r (t 1 ) r (t 0 ) dt = lim. (2.6) t 1 t 0 t0 t 1 t 0 Because it is a derivative of a vector, it s a bit different than the time derivatives you saw in your first calculus class or in Appendix B.1. Nonetheless, the idea behind it is the same. Also, if you re having difficulty making sense of the vector subtraction in Figure 2.3, I urge you to look at Section A.3.2 in the Appendix. Notice that the numerator is a difference between position vectors. Therefore, the numerator itself is a vector (shown in Figure 2.3). And when we divide the difference vector by the time difference, and take the limit, we get another vector, the velocity vector. The velocity vector is shown in Figure 2.3(c). Here are some important observations to note about velocity: Velocity is a vector. According to the definition (2.6), velocity is a difference vector divided by a scalar. As a vector, the velocity has both magnitude and direction. 4

4 The direction of the velocity vector is always tangent to the path. It points in the direction that the object is moving. Units of velocity. Recall that position has units of length (Section 2.1.3). Referring to Equation (2.6), we see that velocity is a length divided by time (length per time). When discussing velocity, we often put it in terms of miles per hour, meters per second. We can express velocity in units of inches per year if we wanted to. Speed. Velocity and speed are not the same thing. Velocity is a vector. Speed is a scalar; it is the magnitude of velocity. It is an instantaneous measure of how much distance is covered per unit of time, a measure of how fast the object is moving. 2.3 Definition: Acceleration Acceleration is critically important in dynamics. To describe how forces hushing and pulling on an object affect the object s motion, we need to understand acceleration. We ll start with a definition: Acceleration is the time derivative of the velocity vector. We can write the acceleration at time t 0 mathematically as ã(t 0 )= dṽ dt ṽ(t 1 ) ṽ(t 0 ) = lim. (2.7) t 1 t 0 t0 t 1 t 0 Since velocity is a the derivative of position with respect to time, we can write acceleration as a second derivative: ã(t 0 )= d2 r dt Acceleration Example # 1 To help us think about what acceleration means, I want us to work through a couple examples. The first is depicted in Figure 2.4, in which we imagine a car driving on a straight, flat road. The t0 car i v = v i v v 2 v 4 t 1 t 2 t 3 t 4 t Figure 2.4: Top view of a car driving on a straight flat road. figure also shows a plot of the car s speed v as a function of time. The car s velocity vector is given 5

5 by ṽ = v î. (2.8) Initially, the car is stopped at a stop sign. It is motionless. Then, at time t 1, the car s speed begins increasing linearly. At time t 2, the car reaches and then temporarily maintains a constant speed v 2.Attimet 3, suppose that the driver notices a police cruiser and immediately begins slowing down. At time t 4, the car reaches the speed limit v 4, and then maintains that speed. The objective of this exercise is to find the acceleration of the car as a function of time. Using (2.8) and our definition of acceleration (2.7), we get ã = ṽ = v î. (2.9) Thus, acceleration can be obtained by simply taking the time derivative of the speed curve in Figure 2.4. Our plot of a = v as a function of time is shown in Figure 2.5. v t 1 t 2 t 3 t 4 t a t Figure 2.5: Plots of the i components of velocity and acceleration. We should be careful in how we discuss these quantities. It is a mistake to say that the a in the plot is acceleration. Why? Because acceleration is a vector. The acceleration vector is ã = a î. So the scalar a is the î component (only non-zero component) of acceleration 1. Note that for t<t 1, the car is motionless and there is no acceleration. From t 1 through t 2,the velocity in the î direction is increasing. Therefore, we have acceleration in the positive î direction. Since speed is increasing at a constant rate (constant slope), the acceleration is constant between t 1 and t 2. The car is cruising its maximum speed between t 2 and t 3. Since that speed is constant (unchanging) in this time interval, the acceleration is zero. Similarly, for t>t 4, acceleration is zero when the car is traveling at a different constant rate, at the speed limit. Between t 3 and t 4, the speed of the car is decreasing. The slope of the v versus t curve is negative. Therefore, the acceleration is in the negative î direction. 1 If my discussion about vectors is confusing I urge you to read through Appendix A. 6

6 Note that the slope of the v versus t is steeper (negative) between t 3 and t 4 than it is between t 1 and t 2. As a result, the acceleration between t 3 and t 4 has a bigger magnitude than the acceleration between t 1 and t 2. If there are aspects of taking derivatives that seem fuzzy to you, I urge you to read Appendix B.1. A Geometric Perspective In calculating the acceleration above, we used Equation (2.9) and then took the derivative of the i component of velocity (a scalar). It might be instructive to try taking a derivative of the velocity vector directly. Recall from (2.7), that the acceleration vector is a ratio. Change in the velocity vector is in the numerator; change in time is in the denominator. In Figure 2.6, I show the plot of the car s speed again, along with four pairs of times at at which we can examine the change in velocity. Each of the pairs of times are spaced a time Δt apart as indicated in the figure. We ll start by looking at part (w) of Figure 2.6. On the left side, I show the velocity vector at times t A and t B. I also show the difference b ) a ). On the right side of Figure 2.6, I show the vector b ) a ), (2.10) Δt which, except for the limit part, is the acceleration vector 2. Because the difference vector b ) a )isinthepositivei direction, the acceleration vector is also in the positive i direction. In Figure 2.6(x), we do the same thing at times t c and t d. Although the velocity vectors c ) and d ) are bigger than a )and b ), the differences d ) c )and b ) a )are the same. This is because the Δts are the same in both cases and the slopes of ) arethesame. Therefore the accelerations are the same. In fact, we get the same acceleration vector in the positive i direction in the entire interval between t 1 and t 2. At times t e and t f, the velocities are the same, and thus the difference f ) e )is0, the zero vector. The numerator is the zero vector, and thus the acceleration is the zero vector. When we repeat the process at t g and t h, we find that the difference vector h ) g ) points in the negative i direction. It s because the velocity is getting smaller. Thus, the acceleration vector is in the negative i direction. Because the difference h ) g ) has bigger magnitude than that of the difference b ) a ), and the two Δts are the same, the negative acceleration in Figure 2.6(z) has bigger magnitude than the positive acceleration in Figure 2.6(w) Acceleration Example # 2 In this next example, I want you to think of a car driving at a constant speed of 55 mph on a flat but winding road. As shown in Figure 2.7, the initial segment of road, up to point A, is straight. From point A to point B, the car makes a gentle left turn along a circular arc of radius R AB. Between points B and C, the track is straight again. Then the car makes a right turn on a circular arc from point C to point D. The radius of the second arc, R CD is smaller than the radius of the first arc R AB. Therefore, the second turn is a bit sharper than the first. After point D, the road is straight again. Again, the objective of the exercise is to find the acceleration of the car as it travels along the path shown. 2 It s rather straightforward to show that, in this case, the acceleration vector and (2.10), without the limit, are identical. 7

7 car i v v = v i t a t b t c t d t e t f t g t h t (w) a ) b ) b ) a ) b ) a ) (x) c ) d ) d ) c ) d ) c ) (y) e ) f ) e ) f ) 0 f ) e ) = 0 (z) g ) h ) h ) g ) h ) g ) Figure 2.6: A geometric perspective for looking at acceleration. 8

8 N W E S R AB B C R CD D car A Figure 2.7: A car that drives at a constant speed on a winding path (top view). A trick question? At first glance, this may appear to be a trick question. In the first sentence of the section, I say that the car is traveling at a constant speed. Well, if the speed is constant, then the time derivative of the speed is zero. Therefore, the acceleration must be zero, right? Be careful! Acceleration is not the derivative of speed. It is the derivative of the velocity vector. Since the speed is constant, the magnitude of the velocity vector does not change. However, the direction of the velocity vector changes, doesn t it? At point A, the car is traveling due East (according to the compass directions labeled in Figure 2.7). At points B and C, the car is traveling northeast. At point D, the car is traveling southeast. Recall from Section 2.2 that the velocity vector is always tangent to the path, pointing in the direction of the car s motion. As the car travels along the curvy path of Figure 2.7, the velocity vector changes because its direction changes. Therefore the acceleration vector, generally, is not zero. Acceleration Due to Path Curvature In Figure 2.8, I show the path (dashed) of the car through the first left turn, and I label two points on the path a and b. We let t a and t b denote the times at which the car passes points a and b. Furthermore, I ve drawn the velocity vectors at these two points: ṽ(t a )andṽ(t b ). Note that the two velocity vectors have the same magnitude (length), because speed is constant it s the same everywhere. However, in terms of direction, we see that velocity is always tangent to the path. as the car moves along the path, the direction of the velocity vector changes. At the lower right side of Figure 2.8, I enlarge the velocity vectors a bit, just so that it s easier to see all the pieces. When we place the two velocity vectors together tail-to-tail, it becomes easy to visualize the difference ṽ(t b ) ṽ(t a ). Then, when we take the velocity difference and divide by the time difference t b t a, we get a vector approximating the acceleration, shown in the upper right corner of the figure. Aha! We see that the acceleration vector appears to point toward the inside part of the curve. Note that our approximation of the acceleration vector is almost perpendicular to the velocity vector. 9

9 Vectors (enlarged) path b ) a ) t b t a car A b a a ) B b ) b ) b ) a ) a ) Figure 2.8: Velocity vectors and differences in the first left turn of the road. A Closer Look at the Direction of Acceleration To examine the direction of the acceleration vector more closely, let s consider the vector triangle containing ṽ(t a ), ṽ(t b ), and ṽ(t b ) ṽ(t a ). I reproduce the triangle in Figure 2.9, even larger, so that we can see the angles better a/2 b ) b ) a ) a a ) 90 - a/2 Figure 2.9: Velocity triangle from Figure 2.8. Here, we let α denote the angle between the two velocity vectors. And since the two velocity vectors have the same magnitude, the two long sides of the triangle have the same length. The triangle is an isosceles triangle. As a consequence, the two other interior angles must be 90 α/2. Therefore, our approximation of the acceleration isn t quite perpendicular to the velocity vector. The angle between the two is 90 α/2 rather than 90. But it s almost perpendicular since α is small. Now recall that the actual acceleration, since it is a derivative, has a limit in it: ã(t a ) = lim t b t a ṽ(t b ) ṽ(t a ) t b t a. (2.11) So when we let t b approach t a in the limit, the two vectors get closer together; the angle α gets smaller. Thus, in the limit, the acceleration vector is perpendicular to the velocity vector. And since the velocity vector is tangent to the path, we can say the acceleration vector is perpendicular to the path. 10

10 Thinking About Assumptions At the beginning of Section 2.3.2, we said that the road between points A and B was a circular path. However, none of the arguments we ve made thus far required the path to be circular. The path just needed to be curved. Our results so far simply state that when an object is moving at a constant speed along a curved path, its acceleration is perpendicular to the path and points toward the inside of the curve. Dependence on Speed At the beginning of Section 2.3.2, I stated that the car was traveling at a constant speed of 55 mph. How does the acceleration differ if the car was going at a constant speed of 110 mph instead? Let s redraw Figure 2.8, but this time we ll do it for the faster speed. The result is in Figure For reference, I have shown the previous vectors from Figure 2.8 in light gray. Vectors (enlarged) car A b ) b ) a ) b ) b a b a a, a a ) a ) Figure 2.10: Velocity vector triangle analogous to that of Figure 2.8, except the car is traveling twice as fast. Previous results are shown in light gray. Recall that when the car was traveling at 55 mph, we defined two points labeled a and b in Figure 2.8. Similarly, we define points a and b in Figure The point a is chosen so that it coincides with point a exactly. Then, point b is chosen so that the time differences are the same, t b t a = t b t a. (2.12) Point b is twice as far down the track than point b because the car is going twice as fast: it covers twice the distance in the same amount of time. The new velocity vector triangle is shown on the right half of Figure Notice that the vectors ṽ(t a ) and ṽ(t b ) are twice as large as the vectors ṽ(t a )andṽ(t b ). If doubling the length of two sides of the velocity triangle were the only effects of doubling the speed, then the difference ṽ(t b ) ṽ(t a ) would double in size as well. But here, we also double the size of the interior angle α =2α. [Recall that point b is twice as far down the circular track.] This causes the difference to double again. As a result, ṽ(t b ) ṽ(t a ) is about four times larger than the original difference ṽ(t b ) ṽ(t a ). Recall that the time differences (2.12) are identical. Therefore the acceleration for the 110 mph case predicted by Figure 2.10 is approximately four times larger in magnitude than the acceleration predicted in the 55 mph case of Figure 2.8. The fact that doubling the speed causes the amplitude to 11

11 quadruple in magnitude suggests that the acceleration magnitude is proportional to speed squared: Dependence on Radius of Curvature ã v 2. (2.13) You may recall in Figure 2.7 that the first curve is rather gentle while the second is sharper. We can quantify the sharpness of the curve by the radius of the circular arc. The smaller the radius, the sharper the curve. Now we can ask the question: How does the acceleration depend on the radius of curvature? In Figure 2.11, we show the gentle left turn as well as the sharper right turn. The radius of the right turn is half as large as the radius for the left turn: R AB =2R CD. We ll assume that the car is traveling at a constant rate of 55 mph as we did originally. R AB C c ) d ) c d D B A a b a ) b ) R CD Vectors (enlarged) b ) c ) b ) a ) a b a ) d ) b ) a ) t b t a d ) c ) t d t c d ) c ) Figure 2.11: Velocity vector triangles for the gentle left turn and the sharper right turn. The velocity vectors for the gentle left turn are the same as those already presented in Figure 2.7. The new information lies on the right side of the figure, where I defined points c and d so that the distance between points c and d (along the circular arc) is the same as the distance between points a and b. Because the car is traveling at the same speed along the entire track, we get t d t c = t b t a. Observe that the velocity vectors ṽ(t c )andṽ(t d ) have the same magnitude, and they have the same magnitude as ṽ(t a )andṽ(t b ). Notice, however, that the direction of the car changes more 12

12 rapidly in the sharper turn. The interior angle β for the right turn is twice as big as the interior angle for the left turn, α. As a consequence, the velocity difference for the sharp turn, ṽ(t d ) ṽ(t c ), is roughly twice as big in magnitude as the velocity difference for the gentle turn, ṽ(t b ) ṽ(t a ). Therefore, our estimates of acceleration come in roughly a two-to-one ratio: ṽ(t d ) ṽ(t c ) t d t c 2 ṽ(t b) ṽ(t a ) t b t a. As we ll show in Section??, the approximation above becomes exact when we take the limit and calculate the derivative properly. Combining this result with the dependence on acceleration expressed in Equation (2.13), we get Acceleration on the Road as a Whole ã v2 R. (2.14) In Figure 2.12, I show acceleration vectors magnitude and direction at several points along the road. The points are roughly equally spaced. C D B A Figure 2.12: Acceleration vectors at several points along the path. The first thing to note is that, in the straight sections of the path, there is no acceleration. The velocity vector is not changing its magnitude or direction. In the curved portions of the track, the acceleration vectors are perpendicular to the path and point toward the center of curvature. Because the right turn is a sharper turn, the acceleration vectors there are larger in magnitude. Something to think about. In this exercise we assumed that the car was traveling along the track from left to right at a constant speed of 55 mph. Now suppose that the car is traveling from right to left at 55 mph. How does the acceleration change under these circumstances? Acceleration, Combining Examples #1 and #2 You ll recall, that in Example 1, the road was straight, but the speed changed. Then, in Example #2, we held the speed constant, but allowed the direction to change. In the first case, the acceleration 13

13 was pointing in the direction of the path. In the second case, the acceleration was perpendicular to the path. When the car is able to execute a more general motion in which it is allowed to change its direction and change its speed, it has both types of acceleration. We can write the acceleration as ã = a t ê t + a n ê n. (2.15) Here, e t and e n are basis vectors that point tangent and perpendicular (normal) to the path respectively. In Figure 2.13, I draw examples of ê t and ê n at different points along the path. e t e n e n e n e t e n en e t e t e t Figure 2.13: Basis vectors for tangential and perpendicular (normal) directions. The tangengential component of acceleration is simply the time derivative of the speed as we found in Section 2.3.1: a t = v. (2.16) The normal component of accelerate is proportional to speed squared divided by radius of curvature. a n v2 R. (2.17) In Chapter???, we will derive the expressions for a t and a n more rigorously Units of Acceleration With position and velocity, we were careful to specify unit. It s a theme we ll continue throughout the semester. We can deduce the units of acceleration by examining the definition in Equation (2.7). Notice that the numerator on the right hand side is a velocity, which has units of length per time. Meanwhile, the denominator has units of time. Therefore, acceleration has units of length per time squared. (L/T 2 ) Now in the previous section, we said that the normal component of acceleration is proportional to v 2 /R. Let s look at the units of v 2 /R. Recall that speed, v, has units of length per time (L/T ), while R is the radius, a length (L). Therefore, [ ] ( v 2 L ) 2 T = R L = L2 T 2 L = L T 2. (2.18) Aha! The quantity v 2 /R is a length per time squared, just like acceleration. This is no coincidence. 14

14 2.4 Take-Aways Below is a list of what I feel to be the most important points that I want you to take away from Chapter Position is a vector. It has both magnitude and direction. 2. Position has units of length. (L) 3. Velocity is a vector. It is the time derivative of the position vector. (a) The direction of the velocity vector points in the direction that the object is moving, tangent to the path. (b) The magnitude of the velocity vector is a measure of how fast the object is moving. 4. Velocity has units of length per time. (L/T ) 5. Speed is the magnitude of the velocity vector. It is a scalar. 6. Acceleration is a vector. It is the time derivative of the velocity vector. It is the second time derivative of the position vector. (a) The component tangent to the path is due to the changing speed of the object. The component magnitude is equal to v. (b) The component normal (perpendicular) to the path is due to the changing direction of the object s velocity. This component points toward the center of curvature and has magnitude that is proportional to v 2 /R, wherer is the radius of curvature. 7. Acceleration has units of length per time squared. (L/T 2 ). 15

### In order to describe motion you need to describe the following properties.

Chapter 2 One Dimensional Kinematics How would you describe the following motion? Ex: random 1-D path speeding up and slowing down In order to describe motion you need to describe the following properties.

### Chapter 4 One Dimensional Kinematics

Chapter 4 One Dimensional Kinematics 41 Introduction 1 4 Position, Time Interval, Displacement 41 Position 4 Time Interval 43 Displacement 43 Velocity 3 431 Average Velocity 3 433 Instantaneous Velocity

### Calculus Vocabulary without the Technical Mumbo Jumbo

Calculus Vocabulary without the Technical Mumbo Jumbo Limits and Continuity By: Markis Gardner Table of Contents Average Rate of Change... 4 Average Speed... 5 Connected Graph... 6 Continuity at a point...

### Motion Graphs. It is said that a picture is worth a thousand words. The same can be said for a graph.

Motion Graphs It is said that a picture is worth a thousand words. The same can be said for a graph. Once you learn to read the graphs of the motion of objects, you can tell at a glance if the object in

### Some Comments on the Derivative of a Vector with applications to angular momentum and curvature. E. L. Lady (October 18, 2000)

Some Comments on the Derivative of a Vector with applications to angular momentum and curvature E. L. Lady (October 18, 2000) Finding the formula in polar coordinates for the angular momentum of a moving

### SPEED, VELOCITY, AND ACCELERATION

reflect Look at the picture of people running across a field. What words come to mind? Maybe you think about the word speed to describe how fast the people are running. You might think of the word acceleration

### Graphical Presentation of Data

Graphical Presentation of Data Guidelines for Making Graphs Titles should tell the reader exactly what is graphed Remove stray lines, legends, points, and any other unintended additions by the computer

### Vectors. Philippe B. Laval. Spring 2012 KSU. Philippe B. Laval (KSU) Vectors Spring /

Vectors Philippe B Laval KSU Spring 2012 Philippe B Laval (KSU) Vectors Spring 2012 1 / 18 Introduction - Definition Many quantities we use in the sciences such as mass, volume, distance, can be expressed

### Unified Lecture # 4 Vectors

Fall 2005 Unified Lecture # 4 Vectors These notes were written by J. Peraire as a review of vectors for Dynamics 16.07. They have been adapted for Unified Engineering by R. Radovitzky. References [1] Feynmann,

### Figure 1.1 Vector A and Vector F

CHAPTER I VECTOR QUANTITIES Quantities are anything which can be measured, and stated with number. Quantities in physics are divided into two types; scalar and vector quantities. Scalar quantities have

### 6. Vectors. 1 2009-2016 Scott Surgent (surgent@asu.edu)

6. Vectors For purposes of applications in calculus and physics, a vector has both a direction and a magnitude (length), and is usually represented as an arrow. The start of the arrow is the vector s foot,

### Taylor Polynomials and Taylor Series Math 126

Taylor Polynomials and Taylor Series Math 26 In many problems in science and engineering we have a function f(x) which is too complicated to answer the questions we d like to ask. In this chapter, we will

### Continuous Functions, Smooth Functions and the Derivative

UCSC AMS/ECON 11A Supplemental Notes # 4 Continuous Functions, Smooth Functions and the Derivative c 2004 Yonatan Katznelson 1. Continuous functions One of the things that economists like to do with mathematical

### A vector is a directed line segment used to represent a vector quantity.

Chapters and 6 Introduction to Vectors A vector quantity has direction and magnitude. There are many examples of vector quantities in the natural world, such as force, velocity, and acceleration. A vector

### One advantage of this algebraic approach is that we can write down

. Vectors and the dot product A vector v in R 3 is an arrow. It has a direction and a length (aka the magnitude), but the position is not important. Given a coordinate axis, where the x-axis points out

### Physics Notes Class 11 CHAPTER 3 MOTION IN A STRAIGHT LINE

1 P a g e Motion Physics Notes Class 11 CHAPTER 3 MOTION IN A STRAIGHT LINE If an object changes its position with respect to its surroundings with time, then it is called in motion. Rest If an object

### 2-1 Position, Displacement, and Distance

2-1 Position, Displacement, and Distance In describing an object s motion, we should first talk about position where is the object? A position is a vector because it has both a magnitude and a direction:

### Chapter 2: Describing Motion

Chapter 2: Describing Motion 1. An auto, starting from rest, undergoes constant acceleration and covers a distance of 1000 meters. The final speed of the auto is 80 meters/sec. How long does it take the

### 1 of 7 9/5/2009 6:12 PM

1 of 7 9/5/2009 6:12 PM Chapter 2 Homework Due: 9:00am on Tuesday, September 8, 2009 Note: To understand how points are awarded, read your instructor's Grading Policy. [Return to Standard Assignment View]

### Ground Rules. PC1221 Fundamentals of Physics I. Kinematics. Position. Lectures 3 and 4 Motion in One Dimension. Dr Tay Seng Chuan

Ground Rules PC11 Fundamentals of Physics I Lectures 3 and 4 Motion in One Dimension Dr Tay Seng Chuan 1 Switch off your handphone and pager Switch off your laptop computer and keep it No talking while

### 4. How many integers between 2004 and 4002 are perfect squares?

5 is 0% of what number? What is the value of + 3 4 + 99 00? (alternating signs) 3 A frog is at the bottom of a well 0 feet deep It climbs up 3 feet every day, but slides back feet each night If it started

### Lab 2: Vector Analysis

Lab 2: Vector Analysis Objectives: to practice using graphical and analytical methods to add vectors in two dimensions Equipment: Meter stick Ruler Protractor Force table Ring Pulleys with attachments

### Representing Vector Fields Using Field Line Diagrams

Minds On Physics Activity FFá2 5 Representing Vector Fields Using Field Line Diagrams Purpose and Expected Outcome One way of representing vector fields is using arrows to indicate the strength and direction

### Graphing Motion. Every Picture Tells A Story

Graphing Motion Every Picture Tells A Story Read and interpret motion graphs Construct and draw motion graphs Determine speed, velocity and accleration from motion graphs If you make a graph by hand it

### 1 of 10 11/23/2009 6:37 PM

hapter 14 Homework Due: 9:00am on Thursday November 19 2009 Note: To understand how points are awarded read your instructor's Grading Policy. [Return to Standard Assignment View] Good Vibes: Introduction

### 88 CHAPTER 2. VECTOR FUNCTIONS. . First, we need to compute T (s). a By definition, r (s) T (s) = 1 a sin s a. sin s a, cos s a

88 CHAPTER. VECTOR FUNCTIONS.4 Curvature.4.1 Definitions and Examples The notion of curvature measures how sharply a curve bends. We would expect the curvature to be 0 for a straight line, to be very small

### 2. THE x-y PLANE 7 C7

2. THE x-y PLANE 2.1. The Real Line When we plot quantities on a graph we can plot not only integer values like 1, 2 and 3 but also fractions, like 3½ or 4¾. In fact we can, in principle, plot any real

### Parametric Curves, Vectors and Calculus. Jeff Morgan Department of Mathematics University of Houston

Parametric Curves, Vectors and Calculus Jeff Morgan Department of Mathematics University of Houston jmorgan@math.uh.edu Online Masters of Arts in Mathematics at the University of Houston http://www.math.uh.edu/matweb/grad_mam.htm

### Euclidean Geometry. We start with the idea of an axiomatic system. An axiomatic system has four parts:

Euclidean Geometry Students are often so challenged by the details of Euclidean geometry that they miss the rich structure of the subject. We give an overview of a piece of this structure below. We start

### Chapter 4 Online Appendix: The Mathematics of Utility Functions

Chapter 4 Online Appendix: The Mathematics of Utility Functions We saw in the text that utility functions and indifference curves are different ways to represent a consumer s preferences. Calculus can

### 2.2. Instantaneous Velocity

2.2. Instantaneous Velocity toc Assuming that your are not familiar with the technical aspects of this section, when you think about it, your knowledge of velocity is limited. In terms of your own mathematical

### 1 Error in Euler s Method

1 Error in Euler s Method Experience with Euler s 1 method raises some interesting questions about numerical approximations for the solutions of differential equations. 1. What determines the amount of

### Average speed, average velocity, and instantaneous velocity

Average speed, average velocity, and instantaneous velocity Calculating average speed from distance traveled and time We define the average speed, v av, as the total distance traveled divided by the time

### Microeconomic Theory: Basic Math Concepts

Microeconomic Theory: Basic Math Concepts Matt Van Essen University of Alabama Van Essen (U of A) Basic Math Concepts 1 / 66 Basic Math Concepts In this lecture we will review some basic mathematical concepts

### Geometry Notes PERIMETER AND AREA

Perimeter and Area Page 1 of 57 PERIMETER AND AREA Objectives: After completing this section, you should be able to do the following: Calculate the area of given geometric figures. Calculate the perimeter

### Parallel and Perpendicular. We show a small box in one of the angles to show that the lines are perpendicular.

CONDENSED L E S S O N. Parallel and Perpendicular In this lesson you will learn the meaning of parallel and perpendicular discover how the slopes of parallel and perpendicular lines are related use slopes

### 1.2 ERRORS AND UNCERTAINTIES Notes

1.2 ERRORS AND UNCERTAINTIES Notes I. UNCERTAINTY AND ERROR IN MEASUREMENT A. PRECISION AND ACCURACY B. RANDOM AND SYSTEMATIC ERRORS C. REPORTING A SINGLE MEASUREMENT D. REPORTING YOUR BEST ESTIMATE OF

### MILS and MOA A Guide to understanding what they are and How to derive the Range Estimation Equations

MILS and MOA A Guide to understanding what they are and How to derive the Range Estimation Equations By Robert J. Simeone 1 The equations for determining the range to a target using mils, and with some

### Grade 7 & 8 Math Circles Circles, Circles, Circles March 19/20, 2013

Faculty of Mathematics Waterloo, Ontario N2L 3G Introduction Grade 7 & 8 Math Circles Circles, Circles, Circles March 9/20, 203 The circle is a very important shape. In fact of all shapes, the circle is

### Introduction to Calculus

Introduction to Calculus Contents 1 Introduction to Calculus 3 11 Introduction 3 111 Origin of Calculus 3 112 The Two Branches of Calculus 4 12 Secant and Tangent Lines 5 13 Limits 10 14 The Derivative

### Speed, velocity and acceleration

Chapter Speed, velocity and acceleration Figure.1 What determines the maximum height that a pole-vaulter can reach? 1 In this chapter we look at moving bodies, how their speeds can be measured and how

### Lecture L3 - Vectors, Matrices and Coordinate Transformations

S. Widnall 16.07 Dynamics Fall 2009 Lecture notes based on J. Peraire Version 2.0 Lecture L3 - Vectors, Matrices and Coordinate Transformations By using vectors and defining appropriate operations between

### Review Sheet for Third Midterm Mathematics 1300, Calculus 1

Review Sheet for Third Midterm Mathematics 1300, Calculus 1 1. For f(x) = x 3 3x 2 on 1 x 3, find the critical points of f, the inflection points, the values of f at all these points and the endpoints,

### Session 6 Area. area midline similar figures

Key Terms in This Session Session 6 Area Previously Introduced scale factor New in This Session area midline similar figures Introduction Area is a measure of how much surface is covered by a particular

### Newton s Laws. Physics 1425 lecture 6. Michael Fowler, UVa.

Newton s Laws Physics 1425 lecture 6 Michael Fowler, UVa. Newton Extended Galileo s Picture of Galileo said: Motion to Include Forces Natural horizontal motion is at constant velocity unless a force acts:

### Congruence. Set 5: Bisectors, Medians, and Altitudes Instruction. Student Activities Overview and Answer Key

Instruction Goal: To provide opportunities for students to develop concepts and skills related to identifying and constructing angle bisectors, perpendicular bisectors, medians, altitudes, incenters, circumcenters,

### -2- Reason: This is harder. I'll give an argument in an Addendum to this handout.

LINES Slope The slope of a nonvertical line in a coordinate plane is defined as follows: Let P 1 (x 1, y 1 ) and P 2 (x 2, y 2 ) be any two points on the line. Then slope of the line = y 2 y 1 change in

### 2 Session Two - Complex Numbers and Vectors

PH2011 Physics 2A Maths Revision - Session 2: Complex Numbers and Vectors 1 2 Session Two - Complex Numbers and Vectors 2.1 What is a Complex Number? The material on complex numbers should be familiar

### Geometry and Measurement

The student will be able to: Geometry and Measurement 1. Demonstrate an understanding of the principles of geometry and measurement and operations using measurements Use the US system of measurement for

### 2.4 Motion and Integrals

2 KINEMATICS 2.4 Motion and Integrals Name: 2.4 Motion and Integrals In the previous activity, you have seen that you can find instantaneous velocity by taking the time derivative of the position, and

### Lesson 8: Velocity. Displacement & Time

Lesson 8: Velocity Two branches in physics examine the motion of objects: Kinematics: describes the motion of objects, without looking at the cause of the motion (kinematics is the first unit of Physics

### L 2 : x = s + 1, y = s, z = 4s + 4. 3. Suppose that C has coordinates (x, y, z). Then from the vector equality AC = BD, one has

The line L through the points A and B is parallel to the vector AB = 3, 2, and has parametric equations x = 3t + 2, y = 2t +, z = t Therefore, the intersection point of the line with the plane should satisfy:

### The Dot and Cross Products

The Dot and Cross Products Two common operations involving vectors are the dot product and the cross product. Let two vectors =,, and =,, be given. The Dot Product The dot product of and is written and

### Understanding the motion of the Universe. Motion, Force, and Gravity

Understanding the motion of the Universe Motion, Force, and Gravity Laws of Motion Stationary objects do not begin moving on their own. In the same way, moving objects don t change their movement spontaneously.

### Review of Fundamental Mathematics

Review of Fundamental Mathematics As explained in the Preface and in Chapter 1 of your textbook, managerial economics applies microeconomic theory to business decision making. The decision-making tools

### General Physics 1. Class Goals

General Physics 1 Class Goals Develop problem solving skills Learn the basic concepts of mechanics and learn how to apply these concepts to solve problems Build on your understanding of how the world works

### Unit 11 Additional Topics in Trigonometry - Classwork

Unit 11 Additional Topics in Trigonometry - Classwork In geometry and physics, concepts such as temperature, mass, time, length, area, and volume can be quantified with a single real number. These are

### VELOCITY, ACCELERATION, FORCE

VELOCITY, ACCELERATION, FORCE velocity Velocity v is a vector, with units of meters per second ( m s ). Velocity indicates the rate of change of the object s position ( r ); i.e., velocity tells you how

### Session 7 Bivariate Data and Analysis

Session 7 Bivariate Data and Analysis Key Terms for This Session Previously Introduced mean standard deviation New in This Session association bivariate analysis contingency table co-variation least squares

### Exam 1 Review Questions PHY 2425 - Exam 1

Exam 1 Review Questions PHY 2425 - Exam 1 Exam 1H Rev Ques.doc - 1 - Section: 1 7 Topic: General Properties of Vectors Type: Conceptual 1 Given vector A, the vector 3 A A) has a magnitude 3 times that

### Lecture L6 - Intrinsic Coordinates

S. Widnall, J. Peraire 16.07 Dynamics Fall 2009 Version 2.0 Lecture L6 - Intrinsic Coordinates In lecture L4, we introduced the position, velocity and acceleration vectors and referred them to a fixed

### Module 1 : A Crash Course in Vectors Lecture 2 : Coordinate Systems

Module 1 : A Crash Course in Vectors Lecture 2 : Coordinate Systems Objectives In this lecture you will learn the following Define different coordinate systems like spherical polar and cylindrical coordinates

### Work and Energy. Physics 1425 Lecture 12. Michael Fowler, UVa

Work and Energy Physics 1425 Lecture 12 Michael Fowler, UVa What is Work and What Isn t? In physics, work has a very restricted meaning! Doing homework isn t work. Carrying somebody a mile on a level road

### Chapter 13 Newton s Theory of Gravity

Chapter 13 Newton s Theory of Gravity The textbook gives a good brief account of the period leading up to Newton s Theory of Gravity. I am not going to spend much time reviewing the history but will show

### Chapter 6 Work and Energy

Chapter 6 WORK AND ENERGY PREVIEW Work is the scalar product of the force acting on an object and the displacement through which it acts. When work is done on or by a system, the energy of that system

### Reflection and Refraction

Equipment Reflection and Refraction Acrylic block set, plane-concave-convex universal mirror, cork board, cork board stand, pins, flashlight, protractor, ruler, mirror worksheet, rectangular block worksheet,

### Section V.3: Dot Product

Section V.3: Dot Product Introduction So far we have looked at operations on a single vector. There are a number of ways to combine two vectors. Vector addition and subtraction will not be covered here,

### Bending Stress in Beams

936-73-600 Bending Stress in Beams Derive a relationship for bending stress in a beam: Basic Assumptions:. Deflections are very small with respect to the depth of the beam. Plane sections before bending

### Mechanics 1: Conservation of Energy and Momentum

Mechanics : Conservation of Energy and Momentum If a certain quantity associated with a system does not change in time. We say that it is conserved, and the system possesses a conservation law. Conservation

### Chapter 5 Using Newton s Laws: Friction, Circular Motion, Drag Forces. Copyright 2009 Pearson Education, Inc.

Chapter 5 Using Newton s Laws: Friction, Circular Motion, Drag Forces Units of Chapter 5 Applications of Newton s Laws Involving Friction Uniform Circular Motion Kinematics Dynamics of Uniform Circular

### Chapter 7 Newton s Laws of Motion

Chapter 7 Newton s Laws of Motion 7.1 Force and Quantity of Matter... 1 Example 7.1 Vector Decomposition Solution... 3 7.1.1 Mass Calibration... 4 7.2 Newton s First Law... 5 7.3 Momentum, Newton s Second

### Solving Simultaneous Equations and Matrices

Solving Simultaneous Equations and Matrices The following represents a systematic investigation for the steps used to solve two simultaneous linear equations in two unknowns. The motivation for considering

### Gasses at High Temperatures

Gasses at High Temperatures The Maxwell Speed Distribution for Relativistic Speeds Marcel Haas, 333 Summary In this article we consider the Maxwell Speed Distribution (MSD) for gasses at very high temperatures.

### ELEMENTS OF VECTOR ALGEBRA

ELEMENTS OF VECTOR ALGEBRA A.1. VECTORS AND SCALAR QUANTITIES We have now proposed sets of basic dimensions and secondary dimensions to describe certain aspects of nature, but more than just dimensions

### 8. As a cart travels around a horizontal circular track, the cart must undergo a change in (1) velocity (3) speed (2) inertia (4) weight

1. What is the average speed of an object that travels 6.00 meters north in 2.00 seconds and then travels 3.00 meters east in 1.00 second? 9.00 m/s 3.00 m/s 0.333 m/s 4.24 m/s 2. What is the distance traveled

### PHYSICS 149: Lecture 4

PHYSICS 149: Lecture 4 Chapter 2 2.3 Inertia and Equilibrium: Newton s First Law of Motion 2.4 Vector Addition Using Components 2.5 Newton s Third Law 1 Net Force The net force is the vector sum of all

### Chapter 24 Physical Pendulum

Chapter 4 Physical Pendulum 4.1 Introduction... 1 4.1.1 Simple Pendulum: Torque Approach... 1 4. Physical Pendulum... 4.3 Worked Examples... 4 Example 4.1 Oscillating Rod... 4 Example 4.3 Torsional Oscillator...

### A couple of Max Min Examples. 3.6 # 2) Find the maximum possible area of a rectangle of perimeter 200m.

A couple of Max Min Examples 3.6 # 2) Find the maximum possible area of a rectangle of perimeter 200m. Solution : As is the case with all of these problems, we need to find a function to minimize or maximize

### Lateral Acceleration. Chris Garner

Chris Garner Forward Acceleration Forward acceleration is easy to quantify and understand. Forward acceleration is simply the rate of change in speed. In car terms, the quicker the car accelerates, the

### D.2. The Cartesian Plane. The Cartesian Plane The Distance and Midpoint Formulas Equations of Circles. D10 APPENDIX D Precalculus Review

D0 APPENDIX D Precalculus Review SECTION D. The Cartesian Plane The Cartesian Plane The Distance and Midpoint Formulas Equations of Circles The Cartesian Plane An ordered pair, of real numbers has as its

### Copyright 2011 Casa Software Ltd. www.casaxps.com. Centre of Mass

Centre of Mass A central theme in mathematical modelling is that of reducing complex problems to simpler, and hopefully, equivalent problems for which mathematical analysis is possible. The concept of

### 39 Symmetry of Plane Figures

39 Symmetry of Plane Figures In this section, we are interested in the symmetric properties of plane figures. By a symmetry of a plane figure we mean a motion of the plane that moves the figure so that

### Calculus (6th edition) by James Stewart

Calculus (6th edition) by James Stewart Section 3.8- Related Rates 9. If and find when and Differentiate both sides with respect to. Remember that, and similarly and So we get Solve for The only thing

### Physics 210 Q ( PHYSICS210BRIDGE ) My Courses Course Settings

1 of 16 9/7/2012 1:10 PM Logged in as Julie Alexander, Instructor Help Log Out Physics 210 Q1 2012 ( PHYSICS210BRIDGE ) My Courses Course Settings Course Home Assignments Roster Gradebook Item Library

### D.2. The Cartesian Plane. The Cartesian Plane The Distance and Midpoint Formulas Equations of Circles. D10 APPENDIX D Precalculus Review

D0 APPENDIX D Precalculus Review APPENDIX D. The Cartesian Plane The Cartesian Plane The Distance and Midpoint Formulas Equations of Circles The Cartesian Plane Just as ou can represent real numbers b

### Units, Physical Quantities and Vectors

Chapter 1 Units, Physical Quantities and Vectors 1.1 Nature of physics Mathematics. Math is the language we use to discuss science (physics, chemistry, biology, geology, engineering, etc.) Not all of the

### 5.2 Rotational Kinematics, Moment of Inertia

5 ANGULAR MOTION 5.2 Rotational Kinematics, Moment of Inertia Name: 5.2 Rotational Kinematics, Moment of Inertia 5.2.1 Rotational Kinematics In (translational) kinematics, we started out with the position

### Despite its enormous mass (425 to 900 kg), the Cape buffalo is capable of running at a top speed of about 55 km/h (34 mi/h).

Revised Pages PART ONE Mechanics CHAPTER Motion Along a Line 2 Despite its enormous mass (425 to 9 kg), the Cape buffalo is capable of running at a top speed of about 55 km/h (34 mi/h). Since the top speed

### Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION ( )

a. Using Faraday s law: Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION The overall sign will not be graded. For the current, we use the extensive hints in the

### Scalar versus Vector Quantities. Speed. Speed: Example Two. Scalar Quantities. Average Speed = distance (in meters) time (in seconds) v =

Scalar versus Vector Quantities Scalar Quantities Magnitude (size) 55 mph Speed Average Speed = distance (in meters) time (in seconds) Vector Quantities Magnitude (size) Direction 55 mph, North v = Dx

### Definition: A vector is a directed line segment that has and. Each vector has an initial point and a terminal point.

6.1 Vectors in the Plane PreCalculus 6.1 VECTORS IN THE PLANE Learning Targets: 1. Find the component form and the magnitude of a vector.. Perform addition and scalar multiplication of two vectors. 3.

### Newton s Laws. Newton s Imaginary Cannon. Michael Fowler Physics 142E Lec 6 Jan 22, 2009

Newton s Laws Michael Fowler Physics 142E Lec 6 Jan 22, 2009 Newton s Imaginary Cannon Newton was familiar with Galileo s analysis of projectile motion, and decided to take it one step further. He imagined

### Geometry Unit 6 Areas and Perimeters

Geometry Unit 6 Areas and Perimeters Name Lesson 8.1: Areas of Rectangle (and Square) and Parallelograms How do we measure areas? Area is measured in square units. The type of the square unit you choose

### 100 Math Facts 6 th Grade

100 Math Facts 6 th Grade Name 1. SUM: What is the answer to an addition problem called? (N. 2.1) 2. DIFFERENCE: What is the answer to a subtraction problem called? (N. 2.1) 3. PRODUCT: What is the answer

### Lesson 1: Introducing Circles

IRLES N VOLUME Lesson 1: Introducing ircles ommon ore Georgia Performance Standards M9 12.G..1 M9 12.G..2 Essential Questions 1. Why are all circles similar? 2. What are the relationships among inscribed

### EXPERIMENT 3 Analysis of a freely falling body Dependence of speed and position on time Objectives

EXPERIMENT 3 Analysis of a freely falling body Dependence of speed and position on time Objectives to verify how the distance of a freely-falling body varies with time to investigate whether the velocity

### 1.3.1 Position, Distance and Displacement

In the previous section, you have come across many examples of motion. You have learnt that to describe the motion of an object we must know its position at different points of time. The position of an

### Chapter 6 Circular Motion

Chapter 6 Circular Motion 6.1 Introduction... 1 6.2 Cylindrical Coordinate System... 2 6.2.1 Unit Vectors... 3 6.2.2 Infinitesimal Line, Area, and Volume Elements in Cylindrical Coordinates... 4 Example