Chapter 3 Newton s First Law of Motion Inertia Exercises 31 Aristotle on Motion (pages 29 30) Fill in the blanks with the correct terms 1 Aristotle divided motion into two types: and 2 Natural motion on Earth was once thought to be either or 3 Aristotle thought that it was natural for heavy things to and for light things to 4 Aristotle also thought that motion was natural for objects beyond Earth and that the planets and stars moved in perfect circles around 5 What force was thought to have caused a horse and cart to experience violent motion? 6 Before the 1500s, the proper state of objects was thought to be one of, unless they were being pushed or pulled or were moving toward their natural resting place 7 Is the following statement true or false? Early thinkers thought that violent motion was imposed motion 8 Is the following statement true or false? It was commonly thought by many ancient thinkers that if an object moved against its nature, then a force of some kind was responsible 32 Copernicus and the Moving Earth (page 30) Determine if each of the following statements is true or false 9 Copernicus thought that Earth and other planets move around the sun 10 Copernicus thought that Earth was at the center of the universe 11 Copernicus did not publish his ideas until he was near death 12 Copernicus lived a long and happy life after his works were published 13 Why did Copernicus do most of his work in secret? 33 Galileo on Motion (pages 30 32) 14 What was one of Galileo s great contributions to physics? 15 A force is any or 16 Explain what friction is and how it acts 17 In the drawings below, describe each type of slope on the top line On the bottom line, describe the slope s affect on speed a b c 18 Based on his experiments with rolling balls, Galileo was able to conclude that when friction is present, a is needed to keep an object moving 19 Describe the property of inertia in your own words 34 Newton s Law of Inertia (pages 33 35) 20 What is another name for Newton s first law of motion? 21 State Newton s first law of motion 22 Use Newton s first law of motion to explain what happens to dishes on a table when the tablecloth is quickly pulled from beneath them 23 Objects in a state of rest tend to remain at rest; only a will change that state 24 Use Newton s first law of motion to explain why an air hockey puck slides on the game table with no apparent loss in speed Name two things that can cause the puck to change its state of motion 25 Once an object is moving in a force-free environment, for how long will it move in a straight line?
35 Mass A Measure of Inertia (pages 36 38) 26 Circle the letter of each sentence that is true about the mass of an object a The amount of inertia an object has depends on its mass b The more mass an object has, the greater its inertia c Volume and mass are the same quantity d Mass is usually measured in kilograms 27 Which item below has more mass? Which has more volume? Which has the greater inertia? 28 Is the following sentence true or false? Mass is a measure of the gravitational force acting on an object 29 is a measure of the amount of material in an object and depends on the number of and kind of atoms that compose it 30 Is the following sentence true or false? A stone has the same mass on Earth and on the moon, but its weight is less on the moon 31 is the quantity of matter in an object 32 is the force of gravity on an object Match each phrase with the correct word Phrase Word 33 traditional unit of weight a kilogram in the United States b mass 34 measure of matter in most c pound parts of the world d newton 35 SI unit of mass 36 SI unit of force 36 The Moving Earth Again (pages 38 39) 37 If Earth is rotating at 30 km/s, explain how a bird sitting on a tree can drop down vertically and grab a worm that is crawling on the ground Chapter 6 Newton s Second Law of Motion Force and Acceleration Exercises 61 Force Causes Acceleration (page 87) 1 When a hockey puck is struck with a hockey stick, a(n) acts on the puck and the puck 2 Circle the letter of the type of force that causes acceleration a balanced b negligible c zero d unbalanced 3 The combination of forces acting on an object is known as the force 4 The acceleration of an object is directly proportional to the net force acting on it This means that, as the net force acting on the object increases, the acceleration of the object 5 Circle the letter of each statement about force and acceleration that is true a Balanced forces cause constant acceleration b The forces acting on an object at rest are unbalanced c A net force acting on an object causes acceleration d Force is not required for an object to accelerate 6 Two shopping carts of equal mass are pushed by two different people One cart accelerates three times as fast as the other cart Describe the forces acting on each cart 62 Mass Resists Acceleration (page 87) 7 For a constant force, how does an increase in an object s mass affect its acceleration? 8 What does it mean for two quantities to be inversely proportional to one another? 9 Circle the letter showing how mass and acceleration are related a acceleration ~ mass b acceleration ~ 1/mass c acceleration ~ mass 2 d acceleration ~ 1 2 mass 63 Newton s Second Law (pages 88 89) 10 Circle the letter of each quantity related by Newton s second law a mass b force c time d acceleration
11 Circle the letter of each statement related to Newton s second law that is true a Acceleration is directly proportional to the net force b The direction of acceleration is the same as the net force c Acceleration is inversely proportional to mass d Net force and mass are always equal 12 When using the equation for Newton s second law, if force is measured in newtons, then the unit for acceleration is and the unit for mass is 13 Is the following sentence true or false? The acceleration of an object is equal to the net force acting on it divided by the object s mass 14 A 100-N force is used to accelerate a large push cart across the floor Circle the letter of the force required to accelerate the push cart twice as fast a 50 N b 100 N c 150 N d 200 N 15 An object accelerates when a net force is applied to it Circle the letter describing the conditions that would double the object s acceleration a doubling the mass b halving the force c doubling the mass and halving the force d halving the mass 16 During a lab experiment, a net force is applied to an object and the object accelerates The mass of the object is then doubled, and the net force applied to it also doubles Describe the object s acceleration 17 Circle the letter of the equation that describes Newton s second law of motion a a = c F F m b F = ma 2 = a d F = 1 m 2 (am)2 64 Friction (page 90 91) 18 Describe what causes friction between two solid surfaces 19 Is the following sentence true or false? Friction does not depend on the types of materials in contact with each other 20 Is the following sentence true or false? Friction depends on how much the materials in contact are pushed together 21 The figure above shows where an out-of-control car might strike a concrete road divider In terms of friction, explain why the concrete barrier is superior to the steel barrier in the figure 22 Substances that are liquids or gases are also called 23 Is the following sentence true or false? When friction is present, an object can move with constant velocity even when an outside force is applied 24 A is a diagram in which all of the forces acting on an object are shown 65 Applying Force Pressure (pages 91 92) 25 Circle the letter of each quantity related to pressure a time b force c weight d area 26 Circle the letter that best describes pressure a the applied force that acts on an object b force per unit of area c the area to which a force is applied d force times surface area 27 Imagine standing on a bathroom scale on two feet and then one foot Describe the force and pressure exerted in each case 28 As the area a force acts on increases, the force exerted on each unit of area 29 What is the equation for pressure when the force is perpendicular to the surface area? 30 Circle the letter that describes the unit of pressure known as a pascal a newtons area b newton meter c newtons per square meter d square meters per second
31 Look at the two books resting on a shelf in the illustration shown below Assume the two books are identical Circle the letter of each statement about the two books that is true a Both books have the same mass b Both books exert the same force on the shelf c Both books exert the same pressure on the shelf d Both books have the same weight 66 Free Fall Explained (pages 93 95) 32 An object dropped in air that experiences no air resistance is said to be in 33 A 1-kg river rock and a 10-kg small boulder are dropped from the back of a truck at the same time Identify which rock will strike the ground first 34 When an object is in free fall, the only force acting on the object is 35 Circle the letter of each statement about freely falling objects that is true a They all fall with the same acceleration b The net force acting on them is their weight c Their weight-to-mass ratios are always the same d Their acceleration is g, the acceleration due to gravity 67 Falling and Air Resistance (pages 95 97) 36 Identify the conditions needed for a feather and coin to fall at the same rate 37 Circle the letter of each factor that affects the amount of air resistance experienced by an object a time in contact with the air b speed of object through the air c surface area of object d weight of object 38 Circle the letter that describes the forces that are in balance when an object reaches its terminal speed a mass and air resistance b air resistance and friction c friction and mass d weight and air resistance 39 Define terminal speed and terminal velocity Chapter 7 Newton s Third Law of Motion Action and Reaction Exercises 71 Forces and Interactions (page 107) 1 A force is always part of a(n) that involves another force 2 Define interaction 3 Describe the interaction forces between a nail and a hammer that hits it 72 Newton s Third Law (page 108) 4 State Newton s third law 5 Is the following sentence true or false? It doesn t matter which force we call action and which we call reaction 6 Action and reaction forces are equal in and opposite in 7 Is the following sentence true or false? In every interaction, the forces always occur in pairs 8 Complete the table by writing the reaction for each action Action Reaction When you walk, you push against the floor The tires of a car push against the road When swimming, you push the water backward A dog wags its tail You push on a wall When a batter swings, the bat exerts a force on the ball 9 Use the idea of action and reaction forces to explain why a person trying to walk on ice may not have any forward motion
73 Identifying Action and Reaction (pages 108 109) 10 What are the two steps you can take to identify a pair of action-reaction forces? a b 11 Identify the action reaction forces of a boulder falling off a cliff by answering the following questions a What are the two interacting objects? b What is the action of A on B? c What is the action of B on A? 12 Complete the table by identifying the reaction forces In each case, specify the direction of the reaction force Action Reaction As a car moves along a road, the tires of the car push backward against the road As a spaceship moves through space, it pushes gas out behind A ball rolls across a table and exerts a force against a second ball 74 Action and Reaction on Different Masses (pages 110 111) 13 Is the following sentence true or false? If you drop a pencil, the pencil pulls Earth upward with a much smaller force than that with which Earth pulls the pencil downward 14 State Newton s second law 15 When a boulder falls off a cliff toward the ground, Earth accelerates toward the boulder Circle the letter that explains why we don t sense this acceleration a The boulder s pull on Earth is much smaller than Earth s pull on the boulder b Earth s huge mass causes its acceleration to be infinitesimally small c Earth s acceleration is in the same direction as the boulder s acceleration d The boulder s acceleration is much smaller than the Earth s acceleration 16 When a cannonball is fired from a cannon, the force the cannon exerts on the cannonball is exactly and to the force the cannonball exerts on the cannon 17 Name the three factors that you must consider in order to understand why a cannonball moves much faster than the cannon when the cannonball is shot from the cannon 18 The picture above shows a cannonball being shot from a cannon Explain why the change in velocity of the cannonball is much greater than the change in velocity of the cannon 19 How is the acceleration of a rocket similar to the acceleration of a cannonball that is fired from a cannon? 20 Is the following sentence true or false? A rocket is propelled by the impact of exhaust gases against the atmosphere 21 The upward force that causes helicopters, birds, and airplanes to fly is called 22 A helicopter has a lifting force because its blades are shaped to force air particles, and the air forces the blades Match each condition on the left to the result on the right Condition Result 23 Lift equals the helicopter s weight 24 Lift is greater than the helicopter s weight 25 Lift is less than the helicopter s weight a The helicopter moves downward b The helicopter moves upward c The helicopter hovers in midair
26 Describe the action and reaction forces that cause a bird to fly 27 Describe two action reaction pairs that cause an airplane to move upward and forward a b 75 Defining Systems (pages 112 113) 28 In order to understand why action and reaction forces don t cancel to zero, you must consider the involved For questions 29 and 30, refer to the figure below 29 The figure shows a force exerted by an apple The dashed line identifies the system that accelerates because of this force Explain why the force that the orange exerts on the apple doesn t cancel the force that the apple exerts on the orange 30 Suppose the system includes both the orange and the apple Explain why the force of the orange on the apple cancels the force of the apple on the orange 31 Is the following sentence true or false? The trillions and trillions of interatomic forces that hold a baseball together do play a role in accelerating the ball 32 Is the following sentence true or false? If the action reaction forces are internal to a system, then the forces cancel and the system does not accelerate 33 When a football player kicks a ball, the player s foot exerts a force on the ball, and the ball exerts a force on the player s foot Why does the ball accelerate, even though the forces are equal and opposite? 76 The Horse Cart Problem (pages 114 115) 34 Describe the horse cart problem 35 Name the three points of view from which you can consider the horse cart problem a b c 36 The farmer is only concerned with the force that is exerted on the 37 According to the farmer, the on the cart, divided by the of the cart, will produce a(n) 38 The horse believes that the reaction force by the on the horse restrains the horse 39 From the horse s point of view, the horse moves forward by interacting with 40 If the horse in the horse cart system pushes the ground with a greater force than it pulls on the cart, then, and the horse cart system accelerates 41 Consider the horse cart system as a whole a Which action reaction pair contributes nothing to the acceleration of the system? b Which interaction is responsible for moving the system? 77 Action Equals Reaction (page 116) 42 Is the following sentence true or false? You cannot hit a wall any harder than the wall can hit you back 43 Explain why it is impossible to strike a sheet of paper that is held in midair with a force of 200 N 44 For every interaction between things, there is always a pair of oppositely directed forces that are