Ch 7 Kinetic Energy and Work. Question: 7 Problems: 3, 7, 11, 17, 23, 27, 35, 37, 41, 43


 Lily Nichols
 2 years ago
 Views:
Transcription
1 Ch 7 Kinetic Energy and Work Question: 7 Problems: 3, 7, 11, 17, 23, 27, 35, 37, 41, 43
2 Technical definition of energy a scalar quantity that is associated with that state of one or more objects The state of an object describes its position and its motion. motion requires energy: flying a plane requires energy (from the fuel) a thrown ball gets its energy from the thrower
3 One definition of energy is the capacity to do work. This chapter covers kinetic energy, which is just one form of energy, and then work. The workenergy theorem relates the two quantities. SI unit of energy is the Joule 1 J = 1 kg m 2 /s 2 another unit of energy is the calorie
4 Kinetic energy energy associated with motion. Anything that moves has kinetic energy. kinetic energy: K = ½ mv 2 Kinetic energy is related to the mass and the velocity. Eample. A 1 kg ball is thrown with v = 20 m/s K = ½ (1kg)(20m/s) 2 = 200 J
5 Work When you apply a force to an object, you can either accelerate or decelerate the object. Since the velocity changes, the kinetic energy changes. Work is the transfer of energy via a force. Symbol for work is W. Easily confused with weight. Work is a scalar. The unit of work is also the Joule.
6 Relation of work and kinetic energy: Let a force act in the direction on a particle with 1D motion: F =ma Multiply equation by ½ m: v 2 v 2 0 2a d substituting 1 2 mv 2 F ma 1 2 mv 2 0 ma d Yields: 1 2 mv mv 2 0 F d F d is the work
7 Work W = F d Work depends on displacement If there is no displacement, there is no work.  If you are holding a book still in the air, you are doing no work  If you are sitting still in a chair, gravity is doing no work.  If you lean on a wall and the wall does not move, you are doing no work.
8 Only components of forces parallel to the displacement do work. F sin F d F cos W = (F cos ) d W = F d cos The vertical component does no work.
9 Only the component of the force that is along the direction of the displacement, does any work. W = F d cos Work is the dot product between the force and the displacement. W F In this definition: W = F d cos F and d are magnitudes, are always positive d The work will be positive or negative based on the cos.
10 Work kinetic energy theorem W = K or K f = K i + W Positive work increases the kinetic energy. Speed up the object Negative work decreases the kinetic energy. Slows down the object
11 Work done by gravitational force The gravitational force is never turned off, so whenever an object has a change in elevation, there is work done by the gravitational force.. W g = mg d cos Since F g is always down, whenever the object is lowered, F g does positive work. When the object is raised, F g does negative work.
12 W g = mg d cos Since F g is always down, whenever the object is lowered vertically, d is down and = 0 0. F g does positive work. When the object is raised straight up, d is up and = F g does negative work.
13 When raising or lowering an object you have to consider the work done by the applied force and the work done by gravity. K = W a + W g If the initial and final velocities of the object being moved are equal then: W a = W g It does not matter if the K f and K i are zero or not, as long as they are equal. You can lift something at constant velocity, or you can pick up a stationary object and then hold it still.
14 If you have a nonconstant force that picked up an object, calculating your work directly may be tricky. However you can calculate the work done by gravity and then take the opposite of W g. Eample of Olympic snatch. The lift requires two separate pulls requiring different muscle groups. Instead of trying to determine how much force each pull eerted and over what distance, you can instead find the work done by gravity and then take: W a = W g.
15 Eample You lower a bucket down a well, with constant velocity a distance of 8 meters. You eert a constant force of 19.6 N. The bucket has a mass of 2 kg. Find the work done by you, and the work done by gravity. W = mg W = (2kg) g W = 19.6 N 19.6 N W
16 The displacement is down the well. W = (F cos ) Your work: Work by gravity: W y = (19.6 N cos 180) 8m W y = J W g = (19.6 N cos 0) 8m W g = J Notice that the work done by gravity was mgh, where h is the change in height. The net work is zero, the bucket is lowered at a constant velocity.
17 Eample A 500 N force directed 30 degrees above the horizontal is used to pull a 50 kg sled across the ground. The coefficient of friction between the sled and the ground is 0.3. The sled is pulled 5 meters. a) What is the work done by the pulling force b) work done by friction. c) work done by the normal force d) work done by gravity
18 P = 500 N, = 30 0 m = 50 kg = 0.3 = 5 m F f W = mg = 490 N F N W F N + P y = W F N = W P y = mg 500 N (sin 30) F N = (50 kg)g 250 N = 240 N P F f = F N = 0.3*240 N = 72 N
19 W = (F cos ) Work by pulling force: W p = (500 N cos 30) 5 m = 2165 J Work by friction: W f = (72 N cos 180) 5 m = J Work by normal force: W N = (240 N cos 90) 5 m = 0 J Work by gravity: W g = (490 N cos 270) 5 m = 0 J Net work is then 2165 J 360 J = 1805
20 Work by a general variable force When the force is variable we cannot use: W = (F cos ). This is because the work done over each interval, is different. Instead we have to integrate the force over the total displacement to find the work. W i f F( ) d The area under the Force vs. displacement cure is equal to the work. (see fig. 713)
21 Let: and F dr F iˆ diˆ Variable force in 3D F y ˆj dyj ˆ Fzkˆ dzkˆ (the small change in position) The amount of work produced by the force over the small displacement interval dr is: dw F dr F d F dy F dz The work over the total displacement is: rf rf W dw F dr W r i i f F d y r i y y i f z Fydy z z i f Fzdz
22 WorkKinetic Energy Theorem with a variable force The work of a variable force is: W i f F( ) d Using Newton s 2 nd law we rewrite as: ma d = dv m d dt W i f ( ma) d Using the chain rule we have: W W i f dv dt dv d d dt dv d v f 2 2 ( ma) d m vdv mv f mvi v K i 1 2 v 1 2
23 Spring A spring force is a particular type of variable force. Spring forces are important because many forces behave mathematically like spring forces. Spring can be used to apply forces Springs can store energy These can be done by either compression, stretching, or torsion.
24 Springs Ideal, or linear springs follow a rule called: Hooke s Law: Fs =  k Also an ideal spring will have negligible mass. k is called the spring constant. This determines how stiff the spring is. is the distance the spring is deformed (stretched or compressed) from the equilibrium length. The minus sign tells us that this is a restoring force.
25 Restoring force means that the force the spring eerts, is in the opposite direction of the force that deforms the spring. If I pull the bo to the right (stretch the spring), the spring will eert a force to the left. If I push the bo to the left (compress the spring), the spring will eert a force to the right.
26 Spring constant The spring constant, (k), determines how stiff a spring is.  High spring constant Stiff or strong, Hard to stretch or compress  Low spring constant Limp or weak, Easy to stretch or compress  Units for spring constant are force per length: N/m
27 Simple spring eample A spring with a spring constant of 250 N/m has a length of 0.5 meters when un stretched. What magnitude of force is needed to stretch the spring so that is 0.75 meters long? F s =  k F s = (250 N/m)(0.75m 0.5m) = 62.5 N I got rid of the minus sign to show the magnitude. Note that it would take the same amount of force to compress the spring by 0.25 meters.
28 W = (F cos ) assumes a constant amount of force. So this will not work for a spring. The force needed to deform (stretch/compress) a spring increases as the deformation increases. W W W s s s i i f f 1 2 F d kd k ( k)( f i ) ki kf i f d If i =0, the work of a spring force, where is the deformation of the spring: W s =  ½ k 2
29 When a spring is deformed: The work done by the spring will be positive if the spring ends up closer to its relaed length. W s will be negative if the spring ends up further away from its relaed length. W s is zero if the difference of the spring s length to the relaed length is unchanged.
30 Similar to the case of an applied force acting against gravity. We can find the work of an applied force acting against a spring using: K = W a + W s If the ends of the spring are stationary before and after the displacement. then: W a = W s
31 Power Definition of power is the work done per time. W P ave t SI unit of power is the watt (W). 1 watt = 1 J/s (Don t confuse the W for watt with the W for work) Instantaneous power: P dw dt
32 U.S. unit of power is horsepower 1 hp = 746 W For electric power generation/usage, use the kilowatthour. This is the energy transferred in 1hr at the rate of 1kW (1000 J/s). 1kWh = (1000J/s)(3600s) = J
33 General form for power: P P P dw dt Fv cos F v F(cos dt ) d F cos d dt Power is the dot product of the force and velocity vectors. Only components of forces that are parallel to the velocity do work. The power from forces that are perpendicular to the motion is zero.
34 Power Power is related to how fast a force can be applied. Lifting a heavy weight slowly may not require much power. Picking up the same weight quickly will require more power. Weightlifting eamples: compare the power required to perform a bench press and an Olympic snatch.
35 Assume the weights are moved at constant velocities and the applied forces are constant. Bench press: 300 lbs (1335 N), P = F v Range of motion ~ 0.5 m time to raise weight ~3 seconds = F / t = (1335 N)(0.5 m)/(3s) = W The above assumptions lead us to the power being constant, (equal to the average power).
36 Olympic snatch: 100 lbs (445 N) P = F v Range of motion ~ 1.5 m time to raise weight ~1 s = F / t = (445 N)(1.5 m)/(1s) = W Compared to the power in the bench press (222.5 W) Even though the snatch is performed with less weight, it requires more power because of the larger velocity. (Could have found the power by finding the work of the applied force, using W a =  W g. Then using power = work/time.)
37 Bucket Eample You want to lift a 20 kg bucket up a well at a constant velocity of 0.5 m/s. What power is needed to do so? Since the velocity is constant, the upward force you must pull with is equal to the weight of the bucket. P = F v = F v = (20kg)g (0.5 m/s) = 98 W
38 Another bucket eample Again you want to raise the same 20 kg bucket. It is starting from rest, and you want to pull on the bucket so that is has a velocity of 2 m/s. You want to accomplish this over a time interval of 4 seconds. Use Power and the work energy theorem. (net work equals change in kinetic energy.)
39 first find the change in the kinetic energy. K = ½ mv f2 ½ mv 02 = ½ (20kg)(2m/s) 2 K = 40 J Work = 40 J Average power = Work/time = (40 J) /(4s) = 10 W
40 Shamu eample Calculate the average power needed for the whale to speed up. The killer whale has mass of 8000 kg What power is needed to reach speed of 12m/s in a 6 second time interval? Do work energy theorem K = ½ mv f2 ½ mv 02 = ½ (8000kg)(12m/s) 2 K = J Power = ( J)/6 s = W This was neglecting drag. The power is actually higher W (1hp/746W) = 128 hp About the same as a car.
41 Power delivered by elevator motor A 1000 kg elevator carries a load of 800 kg. A constant friction force of 4000 N retards it upward motion. The retarding force behaves similar to friction. What minimum power in kilowatts and horsepower must the motor deliver to lift the fully loaded elevator at a constant speed of 3 m/s?
42 Elevator Since the speed is constant (3m/s), the acceleration and the sum of all forces equals zero. Find the force (T) the motor must pull with to achieve this motion. F = ma = 0 T F r mg = 0 T = F r + mg = 4000 N + (1800kg)g T = N mg F r T
43 Elevator Now that we know the force the motor must eert we can find the power using P = F v =F v. P = F v = ( N)(3m/s) = W 746 W = 1 hp So P = ( W) (1 hp)/(746 W) = 87 hp
44 Question 8 Problems: 10, 12, 20, 24, 30, 34, 48
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
More informationWeight The weight of an object is defined as the gravitational force acting on the object. Unit: Newton (N)
Gravitational Field A gravitational field as a region in which an object experiences a force due to gravitational attraction Gravitational Field Strength The gravitational field strength at a point in
More informationChapter 6. Work and Energy
Chapter 6 Work and Energy The concept of forces acting on a mass (one object) is intimately related to the concept of ENERGY production or storage. A mass accelerated to a nonzero speed carries energy
More informationphysics 111N work & energy
physics 111N work & energy conservation of energy entirely gravitational potential energy kinetic energy turning into gravitational potential energy gravitational potential energy turning into kinetic
More informationWORK DONE BY A CONSTANT FORCE
WORK DONE BY A CONSTANT FORCE The definition of work, W, when a constant force (F) is in the direction of displacement (d) is W = Fd SI unit is the Newtonmeter (Nm) = Joule, J If you exert a force of
More informationwww.mathsbox.org.uk Displacement (x) Velocity (v) Acceleration (a) x = f(t) differentiate v = dx Acceleration Velocity (v) Displacement x
Mechanics 2 : Revision Notes 1. Kinematics and variable acceleration Displacement (x) Velocity (v) Acceleration (a) x = f(t) differentiate v = dx differentiate a = dv = d2 x dt dt dt 2 Acceleration Velocity
More informationWork Energy & Power. September 2000 Number 05. 1. Work If a force acts on a body and causes it to move, then the force is doing work.
PhysicsFactsheet September 2000 Number 05 Work Energy & Power 1. Work If a force acts on a body and causes it to move, then the force is doing work. W = Fs W = work done (J) F = force applied (N) s = distance
More informationGravitational Potential Energy
Gravitational Potential Energy Consider a ball falling from a height of y 0 =h to the floor at height y=0. A net force of gravity has been acting on the ball as it drops. So the total work done on the
More informationv v ax v a x a v a v = = = Since F = ma, it follows that a = F/m. The mass of the arrow is unchanged, and ( )
Week 3 homework IMPORTANT NOTE ABOUT WEBASSIGN: In the WebAssign versions of these problems, various details have been changed, so that the answers will come out differently. The method to find the solution
More informationChapter 7 WORK, ENERGY, AND Power Work Done by a Constant Force Kinetic Energy and the WorkEnergy Theorem Work Done by a Variable Force Power
Chapter 7 WORK, ENERGY, AND Power Work Done by a Constant Force Kinetic Energy and the WorkEnergy Theorem Work Done by a Variable Force Power Examples of work. (a) The work done by the force F on this
More informationWork, Power, Energy Multiple Choice. PSI Physics. Multiple Choice Questions
Work, Power, Energy Multiple Choice PSI Physics Name Multiple Choice Questions 1. A block of mass m is pulled over a distance d by an applied force F which is directed in parallel to the displacement.
More informationWork, Energy and Power
Work, Energy and Power In this section of the Transport unit, we will look at the energy changes that take place when a force acts upon an object. Energy can t be created or destroyed, it can only be changed
More informationKinetic Energy and Work
PH 13A Fall 009 Kinetic Energy and Work Lecture 1011 11 Chapter 7 (Halliday/Resnick/Walker, Fundamentals of Physics 8 th edition) Chapter 7 Kinetic Energy and Work In this chapter we will introduce the
More information9. The kinetic energy of the moving object is (1) 5 J (3) 15 J (2) 10 J (4) 50 J
1. If the kinetic energy of an object is 16 joules when its speed is 4.0 meters per second, then the mass of the objects is (1) 0.5 kg (3) 8.0 kg (2) 2.0 kg (4) 19.6 kg Base your answers to questions 9
More informationChapter 6. Work and Energy
Chapter 6 Work and Energy ENERGY IS THE ABILITY TO DO WORK = TO APPLY A FORCE OVER A DISTANCE= Example: push over a distance, pull over a distance. Mechanical energy comes into 2 forms: Kinetic energy
More information8. Potential Energy and Conservation of Energy Potential Energy: When an object has potential to have work done on it, it is said to have potential
8. Potential Energy and Conservation of Energy Potential Energy: When an object has potential to have work done on it, it is said to have potential energy, e.g. a ball in your hand has more potential energy
More informationCHAPTER 6 WORK AND ENERGY
CHAPTER 6 WORK AND ENERGY CONCEPTUAL QUESTIONS. REASONING AND SOLUTION The work done by F in moving the box through a displacement s is W = ( F cos 0 ) s= Fs. The work done by F is W = ( F cos θ). s From
More informationWork. Work = Force x parallel distance (parallel component of displacement) F v
Work Work = orce x parallel distance (parallel component of displacement) W k = d parallel d parallel Units: N m= J = " joules" = ( kg m2/ s2) = average force computed over the distance r r When is not
More informationC B A T 3 T 2 T 1. 1. What is the magnitude of the force T 1? A) 37.5 N B) 75.0 N C) 113 N D) 157 N E) 192 N
Three boxes are connected by massless strings and are resting on a frictionless table. Each box has a mass of 15 kg, and the tension T 1 in the right string is accelerating the boxes to the right at a
More informationPhysics Notes Class 11 CHAPTER 6 WORK, ENERGY AND POWER
1 P a g e Work Physics Notes Class 11 CHAPTER 6 WORK, ENERGY AND POWER When a force acts on an object and the object actually moves in the direction of force, then the work is said to be done by the force.
More informationWORKSHEET: KINETIC AND POTENTIAL ENERGY PROBLEMS
WORKSHEET: KINETIC AND POTENTIAL ENERGY PROBLEMS 1. Stored energy or energy due to position is known as Potential energy. 2. The formula for calculating potential energy is mgh. 3. The three factors that
More informationProblem Set 5 Work and Kinetic Energy Solutions
MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department o Physics Physics 8.1 Fall 1 Problem Set 5 Work and Kinetic Energy Solutions Problem 1: Work Done by Forces a) Two people push in opposite directions on
More informationChapter 8: Potential Energy and Conservation of Energy. Work and kinetic energy are energies of motion.
Chapter 8: Potential Energy and Conservation of Energy Work and kinetic energy are energies of motion. Consider a vertical spring oscillating with mass m attached to one end. At the extreme ends of travel
More informationW i f(x i ) x. i=1. f(x i ) x = i=1
Work Force If an object is moving in a straight line with position function s(t), then the force F on the object at time t is the product of the mass of the object times its acceleration. F = m d2 s dt
More informationPhysics 201 Homework 8
Physics 201 Homework 8 Feb 27, 2013 1. A ceiling fan is turned on and a net torque of 1.8 Nm is applied to the blades. 8.2 rad/s 2 The blades have a total moment of inertia of 0.22 kgm 2. What is the
More informationGeneral Physical Science
General Physical Science Chapter 4 Work and Energy Work The work done by a constant force F acting upon an object is the product of the magnitude of the force (or component of the force) and the parallel
More information3 Work, Power and Energy
3 Work, Power and Energy At the end of this section you should be able to: a. describe potential energy as energy due to position and derive potential energy as mgh b. describe kinetic energy as energy
More informationWork 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
More informationPhysics 111: Lecture 4: Chapter 4  Forces and Newton s Laws of Motion. Physics is about forces and how the world around us reacts to these forces.
Physics 111: Lecture 4: Chapter 4  Forces and Newton s Laws of Motion Physics is about forces and how the world around us reacts to these forces. Whats a force? Contact and noncontact forces. Whats a
More informationCurso20122013 Física Básica Experimental I Cuestiones Tema IV. Trabajo y energía.
1. A body of mass m slides a distance d along a horizontal surface. How much work is done by gravity? A) mgd B) zero C) mgd D) One cannot tell from the given information. E) None of these is correct. 2.
More informationChapter 4. Forces and Newton s Laws of Motion. continued
Chapter 4 Forces and Newton s Laws of Motion continued 4.9 Static and Kinetic Frictional Forces When an object is in contact with a surface forces can act on the objects. The component of this force acting
More informationName Period WORKSHEET: KINETIC AND POTENTIAL ENERGY PROBLEMS. 1. Stored energy or energy due to position is known as energy.
Name Period Date WORKSHEET: KINETIC AND POTENTIAL ENERGY PROBLEMS 1. Stored energy or energy due to position is known as energy. 2. The formula for calculating potential energy is. 3. The three factors
More informationVELOCITY, 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
More informationMidterm Solutions. mvr = ω f (I wheel + I bullet ) = ω f 2 MR2 + mr 2 ) ω f = v R. 1 + M 2m
Midterm Solutions I) A bullet of mass m moving at horizontal velocity v strikes and sticks to the rim of a wheel a solid disc) of mass M, radius R, anchored at its center but free to rotate i) Which of
More informationWork, Energy and Power Practice Test 1
Name: ate: 1. How much work is required to lift a 2kilogram mass to a height of 10 meters?. 5 joules. 20 joules. 100 joules. 200 joules 5. ar and car of equal mass travel up a hill. ar moves up the hill
More informationObjective: Work Done by a Variable Force Work Done by a Spring. Homework: Assignment (125) Do PROBS # (64, 65) Ch. 6, + Do AP 1986 # 2 (handout)
Double Date: Objective: Work Done by a Variable Force Work Done by a Spring Homework: Assignment (125) Do PROBS # (64, 65) Ch. 6, + Do AP 1986 # 2 (handout) AP Physics B Mr. Mirro Work Done by a Variable
More informationChapter 7: Momentum and Impulse
Chapter 7: Momentum and Impulse 1. When a baseball bat hits the ball, the impulse delivered to the ball is increased by A. follow through on the swing. B. rapidly stopping the bat after impact. C. letting
More informationAt the skate park on the ramp
At the skate park on the ramp 1 On the ramp When a cart rolls down a ramp, it begins at rest, but starts moving downward upon release covers more distance each second When a cart rolls up a ramp, it rises
More informationPhysics Midterm Review Packet January 2010
Physics Midterm Review Packet January 2010 This Packet is a Study Guide, not a replacement for studying from your notes, tests, quizzes, and textbook. Midterm Date: Thursday, January 28 th 8:1510:15 Room:
More informationWork and Conservation of Energy
Work and Conservation of Energy Topics Covered: 1. The definition of work in physics. 2. The concept of potential energy 3. The concept of kinetic energy 4. Conservation of Energy General Remarks: Two
More informationBHS Freshman Physics Review. Chapter 2 Linear Motion Physics is the oldest science (astronomy) and the foundation for every other science.
BHS Freshman Physics Review Chapter 2 Linear Motion Physics is the oldest science (astronomy) and the foundation for every other science. Galileo (15641642): 1 st true scientist and 1 st person to use
More informationLecture 07: Work and Kinetic Energy. Physics 2210 Fall Semester 2014
Lecture 07: Work and Kinetic Energy Physics 2210 Fall Semester 2014 Announcements Schedule next few weeks: 9/08 Unit 3 9/10 Unit 4 9/15 Unit 5 (guest lecturer) 9/17 Unit 6 (guest lecturer) 9/22 Unit 7,
More informationLesson 39: Kinetic Energy & Potential Energy
Lesson 39: Kinetic Energy & Potential Energy Total Mechanical Energy We sometimes call the total energy of an object (potential and kinetic) the total mechanical energy of an object. Mechanical energy
More informationPhysics 11 Assignment KEY Dynamics Chapters 4 & 5
Physics Assignment KEY Dynamics Chapters 4 & 5 ote: for all dynamics problemsolving questions, draw appropriate free body diagrams and use the aforementioned problemsolving method.. Define the following
More informationIn 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 1D path speeding up and slowing down In order to describe motion you need to describe the following properties.
More informationPhysics 41 HW Set 1 Chapter 15
Physics 4 HW Set Chapter 5 Serway 8 th OC:, 4, 7 CQ: 4, 8 P: 4, 5, 8, 8, 0, 9,, 4, 9, 4, 5, 5 Discussion Problems:, 57, 59, 67, 74 OC CQ P: 4, 5, 8, 8, 0, 9,, 4, 9, 4, 5, 5 Discussion Problems:, 57, 59,
More informationPHYS 211 FINAL FALL 2004 Form A
1. Two boys with masses of 40 kg and 60 kg are holding onto either end of a 10 m long massless pole which is initially at rest and floating in still water. They pull themselves along the pole toward each
More informationName: Partners: Period: Coaster Option: 1. In the space below, make a sketch of your roller coaster.
1. In the space below, make a sketch of your roller coaster. 2. On your sketch, label different areas of acceleration. Put a next to an area of negative acceleration, a + next to an area of positive acceleration,
More informationPhysics: Principles and Applications, 6e Giancoli Chapter 4 Dynamics: Newton's Laws of Motion
Physics: Principles and Applications, 6e Giancoli Chapter 4 Dynamics: Newton's Laws of Motion Conceptual Questions 1) Which of Newton's laws best explains why motorists should buckleup? A) the first law
More informationGround 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
More informationNewton 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:
More informationCh 8 Potential energy and Conservation of Energy. Question: 2, 3, 8, 9 Problems: 3, 9, 15, 21, 24, 25, 31, 32, 35, 41, 43, 47, 49, 53, 55, 63
Ch 8 Potential energ and Conservation of Energ Question: 2, 3, 8, 9 Problems: 3, 9, 15, 21, 24, 25, 31, 32, 35, 41, 43, 47, 49, 53, 55, 63 Potential energ Kinetic energ energ due to motion Potential energ
More informationPHY231 Section 2, Form A March 22, 2012. 1. Which one of the following statements concerning kinetic energy is true?
1. Which one of the following statements concerning kinetic energy is true? A) Kinetic energy can be measured in watts. B) Kinetic energy is always equal to the potential energy. C) Kinetic energy is always
More informationWork, Power, and Energy: Explaining the causes of motion without Newton. KIN335 Spring 2005
Work, Power, and Energy: Explaining the causes of motion without Newton KIN335 Spring 2005 What you should know Definition of work and its characteristics Definition of energy (including kinetic energy
More informationPhysics 125 Practice Exam #3 Chapters 67 Professor Siegel
Physics 125 Practice Exam #3 Chapters 67 Professor Siegel Name: Lab Day: 1. A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the
More informationChapter 28 Fluid Dynamics
Chapter 28 Fluid Dynamics 28.1 Ideal Fluids... 1 28.2 Velocity Vector Field... 1 28.3 Mass Continuity Equation... 3 28.4 Bernoulli s Principle... 4 28.5 Worked Examples: Bernoulli s Equation... 7 Example
More informationConservative forces and the potential energy function. Nonconservative forces and the workenergy theorem
Nonconservative forces and the workenergy theorem Consider an object falling with airresistance. There are two forces to consider; the gravitational force (conservative) and the drag force (nonconservative).
More informationAP Physics C. Oscillations/SHM Review Packet
AP Physics C Oscillations/SHM Review Packet 1. A 0.5 kg mass on a spring has a displacement as a function of time given by the equation x(t) = 0.8Cos(πt). Find the following: a. The time for one complete
More informationSimple Harmonic Motion
Simple Harmonic Motion 1 Object To determine the period of motion of objects that are executing simple harmonic motion and to check the theoretical prediction of such periods. 2 Apparatus Assorted weights
More informationFigure 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
More informationPhysical Quantities and Units
Physical Quantities and Units 1 Revision Objectives This chapter will explain the SI system of units used for measuring physical quantities and will distinguish between vector and scalar quantities. You
More informationPHY231 Section 1, Form B March 22, 2012
1. A car enters a horizontal, curved roadbed of radius 50 m. The coefficient of static friction between the tires and the roadbed is 0.20. What is the maximum speed with which the car can safely negotiate
More informationLecture L2  Degrees of Freedom and Constraints, Rectilinear Motion
S. Widnall 6.07 Dynamics Fall 009 Version.0 Lecture L  Degrees of Freedom and Constraints, Rectilinear Motion Degrees of Freedom Degrees of freedom refers to the number of independent spatial coordinates
More information5. Forces and MotionI. Force is an interaction that causes the acceleration of a body. A vector quantity.
5. Forces and MotionI 1 Force is an interaction that causes the acceleration of a body. A vector quantity. Newton's First Law: Consider a body on which no net force acts. If the body is at rest, it will
More informationAP Physics  Chapter 8 Practice Test
AP Physics  Chapter 8 Practice Test Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A single conservative force F x = (6.0x 12) N (x is in m) acts on
More informationPHYSICS 111 HOMEWORK SOLUTION #10. April 8, 2013
PHYSICS HOMEWORK SOLUTION #0 April 8, 203 0. Find the net torque on the wheel in the figure below about the axle through O, taking a = 6.0 cm and b = 30.0 cm. A torque that s produced by a force can be
More information6 WORK and ENERGY. 6.0 Introduction. 6.1 Work and kinetic energy. Objectives
6 WORK and ENERGY Chapter 6 Work and Energy Objectives After studying this chapter you should be able to calculate work done by a force; be able to calculate kinetic energy; be able to calculate power;
More informationNewton s Law of Motion
chapter 5 Newton s Law of Motion Static system 1. Hanging two identical masses Context in the textbook: Section 5.3, combination of forces, Example 4. Vertical motion without friction 2. Elevator: Decelerating
More informationReview D: Potential Energy and the Conservation of Mechanical Energy
MSSCHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.01 Fall 2005 Review D: Potential Energy and the Conservation of Mechanical Energy D.1 Conservative and Nonconservative Force... 2 D.1.1 Introduction...
More informationExercises on Work, Energy, and Momentum. A B = 20(10)cos98 A B 28
Exercises on Work, Energy, and Momentum Exercise 1.1 Consider the following two vectors: A : magnitude 20, direction 37 North of East B : magnitude 10, direction 45 North of West Find the scalar product
More informationWork, Energy & Momentum Homework Packet Worksheet 1: This is a lot of work!
Work, Energy & Momentum Homework Packet Worksheet 1: This is a lot of work! 1. A student holds her 1.5kg psychology textbook out of a second floor classroom window until her arm is tired; then she releases
More informationPhysics 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
More informationParachute Jumping, Falling, and Landing David C. Arney, Barbra S. Melendez, Debra Schnelle 1
Parachute Jumping, Falling, and Landing David C. Arney, Barbra S. Melendez, Debra Schnelle 1 Introduction It is extremely important that leaders of airborne units understand the safety, medical, and operational
More informationMULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Vector A has length 4 units and directed to the north. Vector B has length 9 units and is directed
More informationAP Physics C Fall Final Web Review
Name: Class: _ Date: _ AP Physics C Fall Final Web Review Multiple Choice Identify the choice that best completes the statement or answers the question. 1. On a position versus time graph, the slope of
More informationWORK, POWER, KINETIC ENERGY
WORK, POWER, KINETIC ENERGY by John S. Ross, Rollins College 1. Introduction.............................................. 1 WORK, POWER, KINETIC ENERGY 2. Work a. Meanings Associated with Work.........................
More informationSerway_ISM_V1 1 Chapter 4
Serway_ISM_V1 1 Chapter 4 ANSWERS TO MULTIPLE CHOICE QUESTIONS 1. Newton s second law gives the net force acting on the crate as This gives the kinetic friction force as, so choice (a) is correct. 2. As
More informationName Class Date. You do twice as much work. b. You lift two identical books one meter above the ground.
Exercises 9.1 Work (pages 145 146) 1. Circle the letter next to the correct mathematical equation for work. work = force distance work = distance force c. work = force distance d. work = force distance
More informationLAB 6: GRAVITATIONAL AND PASSIVE FORCES
55 Name Date Partners LAB 6: GRAVITATIONAL AND PASSIVE FORCES And thus Nature will be very conformable to herself and very simple, performing all the great Motions of the heavenly Bodies by the attraction
More informationWork, Energy & Power. AP Physics B
ork, Energy & Power AP Physics B There are many dierent TYPES o Energy. Energy is expressed in JOULES (J) 4.19 J = 1 calorie Energy can be expressed more speciically by using the term ORK() ork = The Scalar
More informationPhysics 1A Lecture 10C
Physics 1A Lecture 10C "If you neglect to recharge a battery, it dies. And if you run full speed ahead without stopping for water, you lose momentum to finish the race. Oprah Winfrey Static Equilibrium
More informationConceptual Questions: Forces and Newton s Laws
Conceptual Questions: Forces and Newton s Laws 1. An object can have motion only if a net force acts on it. his statement is a. true b. false 2. And the reason for this (refer to previous question) is
More informationExam Three Momentum Concept Questions
Exam Three Momentum Concept Questions Isolated Systems 4. A car accelerates from rest. In doing so the absolute value of the car's momentum changes by a certain amount and that of the Earth changes by:
More informationChapter 07 Test A. Name: Class: Date: Multiple Choice Identify the choice that best completes the statement or answers the question.
Class: Date: Chapter 07 Test A Multiple Choice Identify the choice that best completes the statement or answers the question. 1. An example of a vector quantity is: a. temperature. b. length. c. velocity.
More information10.1 Quantitative. Answer: A Var: 50+
Chapter 10 Energy and Work 10.1 Quantitative 1) A child does 350 J of work while pulling a box from the ground up to his tree house with a rope. The tree house is 4.8 m above the ground. What is the mass
More informationWork and Energy. Work = Force Distance. Work increases the energy of an object. Energy can be converted back to work.
Work and Energy Ch. 6 Work = Force Distance Work increases the energy of an object. Energy can be converted back to work. Therefore, energy and work have the same unit: Newton meter = Nm Energy per gram,
More informationforce (mass)(acceleration) or F ma The unbalanced force is called the net force, or resultant of all the forces acting on the system.
4 Forces 41 Forces and Acceleration Vocabulary Force: A push or a pull. When an unbalanced force is exerted on an object, the object accelerates in the direction of the force. The acceleration is proportional
More informationPHY121 #8 Midterm I 3.06.2013
PHY11 #8 Midterm I 3.06.013 AP Physics Newton s Laws AP Exam Multiple Choice Questions #1 #4 1. When the frictionless system shown above is accelerated by an applied force of magnitude F, the tension
More informationPhysics 2A, Sec B00: Mechanics  Winter 2011 Instructor: B. Grinstein Final Exam
Physics 2A, Sec B00: Mechanics  Winter 2011 Instructor: B. Grinstein Final Exam INSTRUCTIONS: Use a pencil #2 to fill your scantron. Write your code number and bubble it in under "EXAM NUMBER;" an entry
More informationChapter 11 Equilibrium
11.1 The First Condition of Equilibrium The first condition of equilibrium deals with the forces that cause possible translations of a body. The simplest way to define the translational equilibrium of
More informationLAB 6  GRAVITATIONAL AND PASSIVE FORCES
L061 Name Date Partners LAB 6  GRAVITATIONAL AND PASSIVE FORCES OBJECTIVES And thus Nature will be very conformable to herself and very simple, performing all the great Motions of the heavenly Bodies
More informationIdeal Cable. Linear Spring  1. Cables, Springs and Pulleys
Cables, Springs and Pulleys ME 202 Ideal Cable Neglect weight (massless) Neglect bending stiffness Force parallel to cable Force only tensile (cable taut) Neglect stretching (inextensible) 1 2 Sketch a
More information1.3.1 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
More informationTEACHER ANSWER KEY November 12, 2003. Phys  Vectors 11132003
Phys  Vectors 11132003 TEACHER ANSWER KEY November 12, 2003 5 1. A 1.5kilogram lab cart is accelerated uniformly from rest to a speed of 2.0 meters per second in 0.50 second. What is the magnitude
More informationMechanics 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
More informationLab 8: Ballistic Pendulum
Lab 8: Ballistic Pendulum Equipment: Ballistic pendulum apparatus, 2 meter ruler, 30 cm ruler, blank paper, carbon paper, masking tape, scale. Caution In this experiment a steel ball is projected horizontally
More informationKE =? v o. Page 1 of 12
Page 1 of 12 CTEnergy1. A mass m is at the end of light (massless) rod of length R, the other end of which has a frictionless pivot so the rod can swing in a vertical plane. The rod is initially horizontal
More informationFRICTION, WORK, AND THE INCLINED PLANE
FRICTION, WORK, AND THE INCLINED PLANE Objective: To measure the coefficient of static and inetic friction between a bloc and an inclined plane and to examine the relationship between the plane s angle
More informationExam 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
More information