# Newton s Laws of Motion

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 Newton s Laws of Motion FIZ101E Kazım Yavuz Ekşi

2 My contact details: Name: Kazım Yavuz Ekşi Notice: Only s from your ITU account are responded. Office hour: Wednesday Website: Website of the course:

3 Chapter 4 4 NEWTON S LAWS OF MOTION 4.1 Force and Interactions 4.2 Newton s First Law 4.3 Newton s Second Law 4.4 Mass and Weight 4.5 Newton s Third Law 4.6 Free-Body Diagrams

4 Force A force is an interaction between two bodies or between a body and its environment. We always refer to the force that one body exerts on a second body. Force is a vector quantity

5 Contact Forces involve direct contact between two bodies Normal Force: always acts perpendicular to the surface of contact, no matter what the angle of that surface. Friction Force: acts parallel to the surface, in the direction that opposes sliding. Tension Force: force exerted by a stretched rope or cord on an object to which it s attached. The push and pull forces in the previous slide are also contact forces.

6 Long Range Forces act even when the bodies are separated by empty space. The force between two magnets. The force of gravity. The gravitational force that the Earth exerts on a body is called weight.

7 Unit of Force To describe a force vector F, we need to describe the direction in which it acts as well as its magnitude. The magnitude of the force describes how much or how hard the force pushes or pulls. The SI unit of the magnitude of force is the newton, abbreviated N.

8 Typical Force Magnitudes

9 Measuring Force A common instrument for measuring force magnitudes is the spring balance. It is a coil spring enclosed in a case with a pointer attached to one end. When forces are applied to the ends of the spring, it stretches by an amount that depends on the force. We can make a scale for the pointer by using a number of identical bodies with weights of exactly 1 N each.

10 Superposition of Forces Experiment shows that when two forces F 1 and F 2 act at the same time at the same point on a body, the effect on the body s motion is the same as if a single force were acting equal to the vector sum of the original forces: R = F 1 + F 2 Any number of forces applied at a point on a body have the same effect as a single force equal to the vector sum of the forces. R = F 1 + F 2 + F 2 + = F

11 Decomposing a Vector Any force can be replaced by its component vectors, acting at the same point. The idea relies on the possibility of superposition: F = F x + F y

12 Decomposing a Vector into Components It s frequently more convenient to describe a force F in terms of it s x and y components F x and F y. The x component of the resultant vector is the sum of the x components of all forces acting. R x = F x R y = F y

13 A body with no net force on it What happens when the net force on a body is zero? The answer is easy if the body is at rest: the body will remain at rest. But what if the body is in motion?

14 Horizontal Motion If we could eliminate friction completely, the puck would never slow down. Once a body has been set in motion, no net force is needed to keep it moving.

15 Newton s First Law of Motion A body acted on by no net force moves with constant velocity (which may be zero) and zero acceleration.

16 Inertia The tendency of a body to keep moving once it is set in motion results from a property called inertia. In Newton s first law, zero net force is equivalent to no force at all. This is just the principle of superposition of forces. When a body is either at rest or moving with constant velocity (in a straight line with constant speed), we say that the body is in equilibrium. F = 0 body in equilibrium In order this to be satisfied Fx = 0, Fy = 0, Fz = 0 body in equilibrium We are assuming that the body can be represented adequately as a point particle. When the body has finite size, we also have to consider where on the body the forces are applied.

17 Exercise: In the movie Star Wars the captain says: We are to hit a asteroid. The ship must be stopped. Shut down the engines! Does stopping the engines really stop the ship? You are driving a Maserati Gran Turismo S on a straight testing track at a constant speed of 250 km/h. You pass a 1971 Volkswagen Beetle doing a constant 75 km/h. On which car is the net force greater?

18 On an Accelerating Frame-I Suppose you are in a bus that is traveling on a straight road and speeding up. If you could stand in the aisle on roller skates, you would start moving backward relative to the bus as the bus gains speed.

19 On an Accelerating Frame-II If instead the bus was slowing to a stop, you would start moving forward down the aisle.

20 On an Accelerating Frame-III In either case, it looks as though Newton s first law is not obeyed; there is no net force acting on you, yet your velocity changes. What s wrong?

21 Inertial Frames of Reference The point is that the bus is accelerating with respect to the earth and is not a suitable frame of reference for Newton s first law. The First Law of Motion is valid in some frames of reference and not valid in others. A frame of reference in which Newton s first law is valid is called an inertial frame of reference. The Earth is at least approximately an inertial frame of reference, but the bus is not.

22 The Earth is not a completely inertial frame owing to the acceleration associated with its rotation. Ex: The earth has a radius of 6380 km and turns around once on its axis in 24 h. (a) What is the radial acceleration of an object at the Earth s equator? Give your answer in m/s 2 and as a fraction of g? (b) If a rad at the equator is greater than g, objects will fly off the Earth s surface and into space. What would the period of the Earth s rotation have to be for this to occur?

23 The earth is not a completely inertial frame also because of its motion around the sun. Ex: The radius of the Earth s orbit around the Sun (assumed to be circular) is km and the earth travels around this orbit in 365 days. (a) What is the magnitude of the orbital velocity of the earth, in m/s? (b) What is the radial acceleration of the earth toward the sun, in m/s 2?

24 Law of Inertia The Earth is not a completely inertial frame, owing to the acceleration associated with its rotation and its motion around the Sun. But we saw that these effects are quite small. Because Newton s first law is used to define what we mean by an inertial frame of reference, it is sometimes called the law of inertia. If we have an inertial frame of reference A, in which Newton s first law is obeyed, then any second frame of reference B will also be inertial if it moves relative to A with constant velocity. Consider now a third object moving with constant velocity with respect to A. Observers in frames A and B will disagree about the velocity of P, but they will agree that P has a constant velocity (zero acceleration) and has zero net force acting on it.

25 Law of Inertia There no single inertial frame of reference is preferred over all others for formulating Newton s laws. All inertial frames are equivalent. The state of rest and the state of motion with constant velocity are not very different; both occur when the vector sum of forces acting on the body is zero.

26 Test Your Understanding In which of the following situations is there zero net force on the body? (i) an airplane flying due north at a steady 120 m/s and at a constant altitude; (ii) a car driving straight up a hill with a slope 3 at a constant 90 km/h (iii) a hawk circling at a constant 20 km/h at a constant height of 15 m above an open field; (iv) a box with slick, frictionless surfaces in the back of a truck as the truck accelerates forward on a level road at 5 m/s 2.

27 Newton s Second Law We have seen that when the net force is zero the object keeps its velocity (zero acceleration). Second law is about what happens when the net force is not zero? Experiment shows that acceleration is proportional to the net force. We conclude that a net force acting on a body causes the body to accelerate in the same direction as the net force.

28 Circular Motion That the acceleration is proportional to the net force also apply to a body moving along a curved path. Hockey puck moving in a horizontal circle on an ice surface of negligible friction. A rope is attached to the puck and to a stick in the ice The rope exerts an inward tension force of constant magnitude on the puck. The net force and acceleration are both constant in magnitude and directed toward the center of the circle.

29 Mass and Force Experiments show that for any given body, the magnitude of the acceleration is directly proportional to the magnitude of the net force acting on the body. F a The proportionality constant is called the inertial mass, or simply the mass, of the body and denote it by m. Thus F = m a

30 Mass and Inertia Mass is a quantitative measure of inertia. The greater its mass, the more a body resists being accelerated. It takes a smaller engine to accelerate a car than a truck. A car is easier to slow down than a truck.

31 Unit of Mass The SI unit of mass is the kilogram. The kilogram is officially defined to be the mass of a cylinder of platinum-iridium alloy kept in a vault near Paris. We can use this standard kilogram, along with F = m a, to define the newton. One newton is the amount of net force that gives an acceleration of 1 meter per second squared to a body with a mass of 1 kilogram. 1 newton = (1 kilogram)(1 meter per second squared) 1 newton = 1 kg m/s 2

32 Measuring Mass We can also use F = m a to measure mass. Suppose we apply a constant net force F to a body having a known mass m 1 and we find an acceleration of magnitude a 1. We then apply the same force to another body having an unknown mass m 2 and we find an acceleration of magnitude a 2. According to F = m a we have m 1 a 1 = m 2 a 2 m 2 m 1 = a 1 a 2 For the same net force, the ratio of the masses of two bodies is the inverse of the ratio of their accelerations. In principle we could use this idea to measure an unknown mass but it is usually easier to determine mass indirectly by measuring the body s weight.

33 Stating Newton s Second Law The principle of super-position of forces also holds true when the net force is not zero and the body is accelerating. Newton s second law of motion: If a net external force acts on a body, the body accelerates. The direction of acceleration is the same as the direction of the net force. The mass of the body times the acceleration of the body equals the net force vector. F = m a Newton s second law is a fundamental law of nature, the basic relationship between force and motion.

34 Remarks on Newton s Second Law F = m a is a vector relation: Fx = ma x, Fy = ma y, Fz = ma z The statement of Newton s second law refers to external forces. F = m a is valid only when m is constant. Newton s second law is valid only in inertial frames of reference, just like the first law.

35 Using Newton s Second Law Ex: A worker applies a constant horizontal force with magnitude 20 N to a box with mass 40 kg resting on a level floor with negligible friction. What is the acceleration of the box?

36 Using Newton s Second Law First choose a coordinate system and to identify all of the forces acting on the body in question. It s usually convenient to take one axis either along or opposite the direction of the body s acceleration, which in this case is horizontal. The forces acting on the box are (i) the horizontal force F exerted by the worker, of magnitude 20 N; (ii) the weight of the box; and (iii) the upward supporting force n exerted by the floor.

37 Using Newton s Second Law The box doesn t move vertically, so the y-acceleration is zero: a y = 0 Our target variable is the x-acceleration, a x. F x = F = 20 N = ma x a x = 20 N = 0.50 m/s2 40 kg

38 Mass and Weight Weight of a body is the gravitational force that the Earth exerts on the body. The terms mass and weight are often misused and interchanged in everyday conversation. Mass is a scalar quantitiy characterizing the inertial properties of a body. Weight is a vector quantity. Mass and weight are related: Bodies having large mass also have large weight. w = m g where g is the acceleration due to gravity. A large stone is hard to throw because of its large mass, and hard to lift off the ground because of its large weight. Remember that g is the magnitude of g, so g is always a positive number, by definition. Thus w = mg, is the magnitude of the weight and is also always positive.

39 Mass and Weight The concept of mass plays two rather different roles in mechanics: The weight of a body (the gravitational force acting on it) is proportional to its mass; we call the property related to gravitational interactions gravitational mass. On the other hand, we call the inertial property that appears in Newton s second law the inertial mass.

40 Newton s Third Law A force acting on a body is always the result of its interaction with another body, so forces always come in pairs. Experiments show that whenever two bodies interact, the two forces that they exert on each other are always equal in magnitude and opposite in direction. Newton s third law of motion: If body A exerts a force on body B (an action ), then body B exerts a force on body A (a reaction ). These two forces have the same magnitude but are opposite in direction. These two forces act on different bodies. F A on B = F B on A The two forces in an action-reaction pair never act on the same body.

41 Exercise: Three blocks on a plane Three blocks connected by strings are pulled by a force F. What is the acceleration of the system? What are the tensions in the strings?

42 Exercise: Atwood Machine Two blocks connected by a string along a pulley. What is the acceleration of the system? What is the tension in the string?

43 Exercise: Atwood Machine T m 2 g = m 2 a m 1 g T = m 1 a (m 1 m 2 )g = (m 1 + m 2 )a a = m 1 m 2 m 1 + m 2 g T = m 2 (a + g)

44 Exercise: Inclined Plane What is the acceleration of the system? What is the tension in the string?

45 Exercise: Inclined Plane What is the acceleration of the system? What is the tension in the string?

46 Exercise: Dangling Rope A uniform rope of mass M and length L hangs from the limb of a tree. Find the tension a distance x from the bottom.

47 Exercise: Dangling Rope The force diagram for the lower section of the rope is shown in the sketch. The section is pulled up by a force of magnitude T (x), where T (x) is the tension at x. The downward force on the rope is its weight T (x) = Mg(x/L). The total force on the section is zero since it is at rest. Hence T (x) = Mg L x At the bottom of the rope the tension is zero (T (0) = 0), while at the top the tension equals the total weight of the rope (T (L) = Mg).

48 Exercise: Whirling Rope A uniform rope of mass M and length L is pivoted at one end and whirls with uniform angular velocity ω. What is the tension in the rope at distance r from the pivot? Neglect gravity.

49 Exercise: Whirling Rope This example cannot be solved by direct application of Newton s second law. However, by treating each small section of the system as a particle, and taking the limit using calculus, we can obtain a differential equation which leads to the solution. Consider the small section of rope between r and r + r. The length of the section is r and its mass is m = M r/l. Because of its circular motion, the section has a radial acceleration. Therefore, the forces pulling either end of the section cannot be equal, and we conclude that the tension must vary with r. The inward force on the section is T (r), the tension at r, and the outward force is T (r + r). Treating the section as a particle, its inward radial acceleration is rω 2. [This point can be confusing; it is just as reasonable to take the acceleration to be (r + r)ω 2. However, we shall shortly take the limit r 0, and in this limit the two expressions give the same result.]

50 Exercise: Whirling Rope The equation of motion for the section is T (r + r) T (r) = mrω 2 = Mrω2 r L The problem is to find T (r), but we are not yet ready to do this. However, by dividing the last equation by r and taking the limit r 0, we can find an exact expression for dt /dr. dt dr T (r + r) T (r) = lim r 0 r = Mrω2 L To find the tension, we integrate. dt = Mω2 L rdr

51 Exercise: Whirling Rope Integrating we obtain dt = Mω2 L rdr T (r) = C Mω2 2L r 2 where C is an integration constant to be determined by a boundary condition. Since the end of the rope at r = L is free, the tension there must be zero, T (L) = 0. T (r) = Mω2 2L (L2 r 2 )

52 A ball thrown straight up has zero velocity at its highest point. Is the ball in equilibrium at this point? If the two ends of a rope in equilibrium are pulled with forces of equal magnitude and opposite direction, why is the total tension in the rope not zero?

### Chapter 4 Dynamics: Newton s Laws of Motion. Copyright 2009 Pearson Education, Inc.

Chapter 4 Dynamics: Newton s Laws of Motion Force Units of Chapter 4 Newton s First Law of Motion Mass Newton s Second Law of Motion Newton s Third Law of Motion Weight the Force of Gravity; and the Normal

### Newton s Laws of Motion

Section 3.2 Newton s Laws of Motion Objectives Analyze relationships between forces and motion Calculate the effects of forces on objects Identify force pairs between objects New Vocabulary Newton s first

### Chapter 4 Dynamics: Newton s Laws of Motion

Chapter 4 Dynamics: Newton s Laws of Motion Units of Chapter 4 Force Newton s First Law of Motion Mass Newton s Second Law of Motion Newton s Third Law of Motion Weight the Force of Gravity; and the Normal

### Chapter 4 Newton s Laws: Explaining Motion

Chapter 4 Newton s s Laws: Explaining Motion Newton s Laws of Motion The concepts of force, mass, and weight play critical roles. A Brief History! Where do our ideas and theories about motion come from?!

### Homework 4. problems: 5.61, 5.67, 6.63, 13.21

Homework 4 problems: 5.6, 5.67, 6.6,. Problem 5.6 An object of mass M is held in place by an applied force F. and a pulley system as shown in the figure. he pulleys are massless and frictionless. Find

### 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.

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 non-contact forces. Whats a

### Newton s Third Law. object 1 on object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 on object 1

Newton s Third Law! If two objects interact, the force exerted by object 1 on object 2 is equal in magnitude and opposite in direction to the force exerted by object 2 on object 1!! Note on notation: is

### Chapter 3.8 & 6 Solutions

Chapter 3.8 & 6 Solutions P3.37. Prepare: We are asked to find period, speed and acceleration. Period and frequency are inverses according to Equation 3.26. To find speed we need to know the distance traveled

### Chapter 5 Newton s Laws of Motion

Chapter 5 Newton s Laws of Motion Force and Mass Units of Chapter 5 Newton s First Law of Motion Newton s Second Law of Motion Newton s Third Law of Motion The Vector Nature of Forces: Forces in Two Dimensions

### 5. Forces and Motion-I. Force is an interaction that causes the acceleration of a body. A vector quantity.

5. Forces and Motion-I 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

### Newton s Laws of Motion

Physics Newton s Laws of Motion Newton s Laws of Motion 4.1 Objectives Explain Newton s first law of motion. Explain Newton s second law of motion. Explain Newton s third law of motion. Solve problems

### Physics Notes Class 11 CHAPTER 5 LAWS OF MOTION

1 P a g e Inertia Physics Notes Class 11 CHAPTER 5 LAWS OF MOTION The property of an object by virtue of which it cannot change its state of rest or of uniform motion along a straight line its own, is

### Physics 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

### Chapter 4. Forces and Newton s Laws of Motion. continued

Chapter 4 Forces and Newton s Laws of Motion continued Clicker Question 4.3 A mass at rest on a ramp. How does the friction between the mass and the table know how much force will EXACTLY balance the gravity

### 2.1 Force and Motion Kinematics looks at velocity and acceleration without reference to the cause of the acceleration.

2.1 Force and Motion Kinematics looks at velocity and acceleration without reference to the cause of the acceleration. Dynamics looks at the cause of acceleration: an unbalanced force. Isaac Newton was

### Physics: 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 buckle-up? A) the first law

### 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

### circular motion & gravitation physics 111N

circular motion & gravitation physics 111N uniform circular motion an object moving around a circle at a constant rate must have an acceleration always perpendicular to the velocity (else the speed would

### Physics 11 Assignment KEY Dynamics Chapters 4 & 5

Physics Assignment KEY Dynamics Chapters 4 & 5 ote: for all dynamics problem-solving questions, draw appropriate free body diagrams and use the aforementioned problem-solving method.. Define the following

### 356 CHAPTER 12 Bob Daemmrich

Standard 7.3.17: Investigate that an unbalanced force, acting on an object, changes its speed or path of motion or both, and know that if the force always acts toward the same center as the object moves,

### Chapter 5 Newton s Laws of Motion

Chapter 5 Newton s Laws of Motion Sir Isaac Newton (1642 1727) Developed a picture of the universe as a subtle, elaborate clockwork slowly unwinding according to well-defined rules. The book Philosophiae

### 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.

### Chapter 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

### Review Chapters 2, 3, 4, 5

Review Chapters 2, 3, 4, 5 4) The gain in speed each second for a freely-falling object is about A) 0. B) 5 m/s. C) 10 m/s. D) 20 m/s. E) depends on the initial speed 9) Whirl a rock at the end of a string

### QUESTIONS : CHAPTER-5: LAWS OF MOTION

QUESTIONS : CHAPTER-5: LAWS OF MOTION 1. What is Aristotle s fallacy? 2. State Aristotlean law of motion 3. Why uniformly moving body comes to rest? 4. What is uniform motion? 5. Who discovered Aristotlean

### PHY231 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

### 2 Newton s First Law of Motion Inertia

2 Newton s First Law of Motion Inertia Conceptual Physics Instructor Manual, 11 th Edition SOLUTIONS TO CHAPTER 2 RANKING 1. C, B, A 2. C, A, B, D 3. a. B, A, C, D b. B, A, C, D 4. a. A=B=C (no force)

### AP Physics Newton's Laws Practice Test

AP Physics Newton's Laws Practice Test Answers: A,D,C,D,C,E,D,B,A,B,C,C,A,A 15. (b) both are 2.8 m/s 2 (c) 22.4 N (d) 1 s, 2.8 m/s 16. (a) 12.5 N, 3.54 m/s 2 (b) 5.3 kg 1. Two blocks are pushed along a

### Lecture 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,

Week 8 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

### F N A) 330 N 0.31 B) 310 N 0.33 C) 250 N 0.27 D) 290 N 0.30 E) 370 N 0.26

Physics 23 Exam 2 Spring 2010 Dr. Alward Page 1 1. A 250-N force is directed horizontally as shown to push a 29-kg box up an inclined plane at a constant speed. Determine the magnitude of the normal force,

### 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:

### NEWTON S LAWS OF MOTION

NEWTON S LAWS OF MOTION Background: Aristotle believed that the natural state of motion for objects on the earth was one of rest. In other words, objects needed a force to be kept in motion. Galileo studied

### 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

### STAAR Science Tutorial 25 TEK 8.6C: Newton s Laws

Name: Teacher: Pd. Date: STAAR Science Tutorial 25 TEK 8.6C: Newton s Laws TEK 8.6C: Investigate and describe applications of Newton's law of inertia, law of force and acceleration, and law of action-reaction

### Worksheet #1 Free Body or Force diagrams

Worksheet #1 Free Body or Force diagrams Drawing Free-Body Diagrams Free-body diagrams are diagrams used to show the relative magnitude and direction of all forces acting upon an object in a given situation.

### PHY231 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

### v 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

### Conceptual Physics 11 th Edition

Conceptual Physics 11 th Edition Chapter 5: NEWTON S THIRD LAW OF MOTION This lecture will help you understand: Forces and Interactions Newton s Third Law of Motion Summary of Newton s Laws Vectors Forces

### Chapter 4 Dynamics: Newton s Laws of Motion

Chapter 4 Dynamics: Newton s Laws of Motion Units of Chapter 4 Force Newton s First Law of Motion Mass Newton s Second Law of Motion Newton s Third Law of Motion Weight the Force of Gravity; and the NormalForce

### Chapter 4: Newton s Laws: Explaining Motion

Chapter 4: Newton s Laws: Explaining Motion 1. All except one of the following require the application of a net force. Which one is the exception? A. to change an object from a state of rest to a state

### MULTIPLE 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

### Friction and Newton s 3rd law

Lecture 4 Friction and Newton s 3rd law Pre-reading: KJF 4.8 Frictional Forces Friction is a force exerted by a surface. The frictional force is always parallel to the surface Due to roughness of both

### Mass, energy, power and time are scalar quantities which do not have direction.

Dynamics Worksheet Answers (a) Answers: A vector quantity has direction while a scalar quantity does not have direction. Answers: (D) Velocity, weight and friction are vector quantities. Note: weight and

### 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

### PHY121 #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

### C 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

### Physics 125 Practice Exam #3 Chapters 6-7 Professor Siegel

Physics 125 Practice Exam #3 Chapters 6-7 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

### Section 3 Newton s Laws of Motion

Section 3 Newton s Laws of Motion Key Concept Newton s laws of motion describe the relationship between forces and the motion of an object. What You Will Learn Newton s first law of motion states that

### Physics I Honors: Chapter 4 Practice Exam

Physics I Honors: Chapter 4 Practice Exam Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. Which of the following statements does not describe

### This week s homework. 2 parts Quiz on Friday, Ch. 4 Today s class: Newton s third law Friction Pulleys tension. PHYS 2: Chap.

This week s homework. 2 parts Quiz on Friday, Ch. 4 Today s class: Newton s third law Friction Pulleys tension PHYS 2: Chap. 19, Pg 2 1 New Topic Phys 1021 Ch 7, p 3 A 2.0 kg wood box slides down a vertical

### F13--HPhys--Q5 Practice

Name: Class: Date: ID: A F13--HPhys--Q5 Practice Multiple Choice Identify the choice that best completes the statement or answers the question. 1. A vector is a quantity that has a. time and direction.

### At 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

### AP 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

### Centripetal Force. This result is independent of the size of r. A full circle has 2π rad, and 360 deg = 2π rad.

Centripetal Force 1 Introduction In classical mechanics, the dynamics of a point particle are described by Newton s 2nd law, F = m a, where F is the net force, m is the mass, and a is the acceleration.

### Unit 4 Practice Test: Rotational Motion

Unit 4 Practice Test: Rotational Motion Multiple Guess Identify the letter of the choice that best completes the statement or answers the question. 1. How would an angle in radians be converted to an angle

### Work, Energy and Power Practice Test 1

Name: ate: 1. How much work is required to lift a 2-kilogram 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

### CHAPTER 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

### Serway_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 of Newton s Laws

More of Newton s Laws Announcements: Tutorial Assignments due tomorrow. Pages 19-21, 23, 24 (not 22,25) Note Long Answer HW due this week. CAPA due on Friday. Have added together the clicker scores so

### Conceptual Physics Fundamentals

Conceptual Physics Fundamentals Chapter 4: NEWTON S LAWS OF MOTION Newton s Laws of Motion I was only a scalar until you came along and gave me direction. Barbara Wolfe This lecture will help you understand:

### Lecture 6. Weight. Tension. Normal Force. Static Friction. Cutnell+Johnson: 4.8-4.12, second half of section 4.7

Lecture 6 Weight Tension Normal Force Static Friction Cutnell+Johnson: 4.8-4.12, second half of section 4.7 In this lecture, I m going to discuss four different kinds of forces: weight, tension, the normal

### 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

### B) 40.8 m C) 19.6 m D) None of the other choices is correct. Answer: B

Practice Test 1 1) Abby throws a ball straight up and times it. She sees that the ball goes by the top of a flagpole after 0.60 s and reaches the level of the top of the pole after a total elapsed time

### UNIT 2D. Laws of Motion

Name: Regents Physics Date: Mr. Morgante UNIT 2D Laws of Motion Laws of Motion Science of Describing Motion is Kinematics. Dynamics- the study of forces that act on bodies in motion. First Law of Motion

### 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

### Units DEMO spring scales masses

Dynamics the study of the causes and changes of motion Force Force Categories ContactField 4 fundamental Force Types 1 Gravity 2 Weak Nuclear Force 3 Electromagnetic 4 Strong Nuclear Force Units DEMO spring

### 1) The gure below shows the position of a particle (moving along a straight line) as a function of time. Which of the following statements is true?

Physics 2A, Sec C00: Mechanics -- Winter 2011 Instructor: B. Grinstein Final Exam INSTRUCTIONS: Use a pencil #2 to ll your scantron. Write your code number and bubble it in under "EXAM NUMBER;" an entry

### b. Velocity tells you both speed and direction of an object s movement. Velocity is the change in position divided by the change in time.

I. What is Motion? a. Motion - is when an object changes place or position. To properly describe motion, you need to use the following: 1. Start and end position? 2. Movement relative to what? 3. How far

### Lecture Outline Chapter 5. Physics, 4 th Edition James S. Walker. Copyright 2010 Pearson Education, Inc.

Lecture Outline Chapter 5 Physics, 4 th Edition James S. Walker Chapter 5 Newton s Laws of Motion Dynamics Force and Mass Units of Chapter 5 Newton s 1 st, 2 nd and 3 rd Laws of Motion The Vector Nature

### Solution Derivations for Capa #11

Solution Derivations for Capa #11 1) A horizontal circular platform (M = 128.1 kg, r = 3.11 m) rotates about a frictionless vertical axle. A student (m = 68.3 kg) walks slowly from the rim of the platform

### 6: Applications of Newton's Laws

6: Applications of Newton's Laws Friction opposes motion due to surfaces sticking together Kinetic Friction: surfaces are moving relative to each other a.k.a. Sliding Friction Static Friction: surfaces

### 9. 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

### TEACHER ANSWER KEY November 12, 2003. Phys - Vectors 11-13-2003

Phys - Vectors 11-13-2003 TEACHER ANSWER KEY November 12, 2003 5 1. A 1.5-kilogram lab cart is accelerated uniformly from rest to a speed of 2.0 meters per second in 0.50 second. What is the magnitude

### Conceptual 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

### Objective: Equilibrium Applications of Newton s Laws of Motion I

Type: Single Date: Objective: Equilibrium Applications of Newton s Laws of Motion I Homework: Assignment (1-11) Read (4.1-4.5, 4.8, 4.11); Do PROB # s (46, 47, 52, 58) Ch. 4 AP Physics B Mr. Mirro Equilibrium,

### AP Physics Circular Motion Practice Test B,B,B,A,D,D,C,B,D,B,E,E,E, 14. 6.6m/s, 0.4 N, 1.5 m, 6.3m/s, 15. 12.9 m/s, 22.9 m/s

AP Physics Circular Motion Practice Test B,B,B,A,D,D,C,B,D,B,E,E,E, 14. 6.6m/s, 0.4 N, 1.5 m, 6.3m/s, 15. 12.9 m/s, 22.9 m/s Answer the multiple choice questions (2 Points Each) on this sheet with capital

### Newton s Wagon Newton s Laws

Newton s Wagon Newton s Laws What happens when you kick a soccer ball? The kick is the external force that Newton was talking about in his first law of motion. What happens to the ball after you kick it?

### B) 286 m C) 325 m D) 367 m Answer: B

Practice Midterm 1 1) When a parachutist jumps from an airplane, he eventually reaches a constant speed, called the terminal velocity. This means that A) the acceleration is equal to g. B) the force of

### Ch 6 Forces. Question: 9 Problems: 3, 5, 13, 23, 29, 31, 37, 41, 45, 47, 55, 79

Ch 6 Forces Question: 9 Problems: 3, 5, 13, 23, 29, 31, 37, 41, 45, 47, 55, 79 Friction When is friction present in ordinary life? - car brakes - driving around a turn - walking - rubbing your hands together

### HW Set II page 1 of 9 PHYSICS 1401 (1) homework solutions

HW Set II page 1 of 9 4-50 When a large star becomes a supernova, its core may be compressed so tightly that it becomes a neutron star, with a radius of about 20 km (about the size of the San Francisco

### Two-Body System: Two Hanging Masses

Specific Outcome: i. I can apply Newton s laws of motion to solve, algebraically, linear motion problems in horizontal, vertical and inclined planes near the surface of Earth, ignoring air resistance.

### Lab 5: Conservation of Energy

Lab 5: Conservation of Energy Equipment SWS, 1-meter stick, 2-meter stick, heavy duty bench clamp, 90-cm rod, 40-cm rod, 2 double clamps, brass spring, 100-g mass, 500-g mass with 5-cm cardboard square

### 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.

### Chapter 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

### Lecture-IV. Contact forces & Newton s laws of motion

Lecture-IV Contact forces & Newton s laws of motion Contact forces: Force arises from interaction between two bodies. By contact forces we mean the forces which are transmitted between bodies by short-range

### University Physics 226N/231N Old Dominion University. Newton s Laws and Forces Examples

University Physics 226N/231N Old Dominion University Newton s Laws and Forces Examples Dr. Todd Satogata (ODU/Jefferson Lab) satogata@jlab.org http://www.toddsatogata.net/2012-odu Wednesday, September

### Force. A force is a push or a pull. Pushing on a stalled car is an example. The force of friction between your feet and the ground is yet another.

Force A force is a push or a pull. Pushing on a stalled car is an example. The force of friction between your feet and the ground is yet another. Force Weight is the force of the earth's gravity exerted

### 7. Kinetic Energy and Work

Kinetic Energy: 7. Kinetic Energy and Work The kinetic energy of a moving object: k = 1 2 mv 2 Kinetic energy is proportional to the square of the velocity. If the velocity of an object doubles, the kinetic

### Chapter 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

### 1. Newton s Laws of Motion and their Applications Tutorial 1

1. Newton s Laws of Motion and their Applications Tutorial 1 1.1 On a planet far, far away, an astronaut picks up a rock. The rock has a mass of 5.00 kg, and on this particular planet its weight is 40.0

### Physics 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 8:15-10:15 Room:

### Lecture Presentation Chapter 4 Forces and Newton s Laws of Motion

Lecture Presentation Chapter 4 Forces and Newton s Laws of Motion Suggested Videos for Chapter 4 Prelecture Videos Newton s Laws Forces Video Tutor Solutions Force and Newton s Laws of Motion Class Videos

### WORK 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 Newton-meter (Nm) = Joule, J If you exert a force of

### PHYSICS 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

### Forces: Equilibrium Examples

Physics 101: Lecture 02 Forces: Equilibrium Examples oday s lecture will cover extbook Sections 2.1-2.7 Phys 101 URL: http://courses.physics.illinois.edu/phys101/ Read the course web page! Physics 101:

### There are three different properties associated with the mass of an object:

Mechanics Notes II Forces, Inertia and Motion The mathematics of calculus, which enables us to work with instantaneous rates of change, provides a language to describe motion. Our perception of force is

### Force & Motion. Force & Mass. Friction

1 2 3 4 Next Force & Motion The motion of an object can be changed by an unbalanced force. The way that the movement changes depends on the strength of the force pushing or pulling and the mass of the