Chapter Menu Chapter Introduction Lesson 1Lesson 1Describing Motion Lesson 2Lesson 2Forces Lesson 3Lesson 3Newton’s Laws of Motion Chapter Wrap-Up

Chapter Introduction In what ways do forces affect an object’s motion?

Chapter Introduction What do you think? Before you begin, decide if you agree or disagree with each of these statements. As you view this presentation, see if you change your mind about any of the statements.

Chapter Introduction 1.You must use a reference point to describe an object’s motion. 2.An object that is accelerating must be speeding up. 3.Objects must be in contact with one another to exert a force. Do you agree or disagree?

Chapter Introduction 4.Gravity is a force that depends on the masses of two objects and the distance between them. 5.All forces change the motion of objects. 6.The net force on an object is equal to the mass of the object times the acceleration of the object. Do you agree or disagree?

Lesson 1 Reading Guide - KC What information do you need to describe the motion of an object? How are speed, velocity, and acceleration related? How can a graph help you understand the motion of an object? Describing Motion

Lesson 1 Reading Guide - Vocab motion reference point distance displacement Describing Motion speed velocity acceleration

Lesson 1-1 A.Motion 1.Motion is the process of changing position. 2.The starting point used to describe the motion or position of an object is called the reference point. Motion

Lesson Distance is the total length of your path of motion. 4.The distance between your final position and your starting position is displacement. 5.A complete description of motion includes a(n) reference point, your displacement, and your direction. Motion (cont.)

Lesson 1-1 The distance traveled and the displacement from the game to the vending machine differ. Motion (cont.)

Lesson 1-1 Motion (cont.) What information do you need to describe an object’s motion?

Lesson 1-2 B.Speed 1.Speed is the distance an object moves divided by the time it took to move that distance. 2.Speed can be constant or changing. Speed

a.A constant speed is unchanging because the distance traveled per unit of time remains the same. b.Speed is changing when the distance traveled per unit of time does not remain the same. c.Average speed is the ratio of the distance moved and the time it took to move that distance.

Lesson 1-2 Speed (cont.) The girl moves with constant speed during the first 4 seconds. The girl’s speed begins to change between seconds 4 and 5.

Lesson 1-3 C.Velocity 1.The speed and direction of an object’s motion is the velocity of the object. Velocity velocity from Latin velocitatem, means “swiftness or speed”

Lesson 1-3 Often, velocity is shown by using an arrow. The length of the arrow represents the speed of an object, while the direction in which the arrow points represents the direction in which the object is moving.

Lesson 1-3 The velocity of an object changes if the speed changes, the direction changes, or both the speed and the direction change.

Lesson Velocity is often represented by using a(n) arrow. a.The total length of the arrow shows speed. b.The direction of the arrow shows the direction the object moves. Velocity (cont.)

3.When an object’s speed and direction remain the same, the object has constant velocity. 4.Velocity changes when the speed or the direction of the motion of the object changes. 5.The measure of how quickly an object’s velocity changes are called acceleration.

Lesson 1-3 Velocity (cont.) Can an object traveling at a constant speed have a changing velocity? Why or why not?

Lesson 1-4 D.Calculating Acceleration 1.Acceleration can be calculated by dividing the change in velocity by the time it took for the velocity to change. Calculating Acceleration

Lesson 1-4 Calculating Acceleration (cont.)

Lesson 1-4 Calculating Acceleration (cont.) How does acceleration differ from velocity?

Lesson 1-4 When an object speeds up, its final velocity is greater than its initial velocity. When an object speeds up, it has positive acceleration. When an object slows down, the initial velocity is greater than its final velocity. As an object slows down, it has negative acceleration, or deceleration. Calculating Acceleration (cont.)

Lesson 1-5 E.Using Graphs to Represent Motion 1.A(n) displacement-time graph shows time on the x-axis and displacement from a(n) reference point on the y-axis.

Lesson 1-5 a.A line on this type of graph represents average speed. b.The line does not show the actual path of motion.

Lesson 1-5

2.A(n) speed-time graph shows time on the x-axis and speed on the y-axis.

Lesson 1-5 a.A point on the line on this type of graph represents the speed of the object at that time.

b.A(n) horizontal line at y = 0 on a displacement-time graph or a speed-time graph shows that the object is at rest. c.The term constant speed means average speed.

Lesson 1-5

Using Graphs to Represent Motion (cont.) How can a graph help you understand an object’s motion?

Lesson 1 - VS A description of an object’s motion includes a reference point, a direction from the reference point, and a distance.

Lesson 1 - VS Speed is the distance traveled by an object in a unit of time. Velocity includes both speed and direction of motion.

Lesson 1 - VS Acceleration is a change in velocity. Velocity changes when either the speed, the direction, or both the speed and the direction change.

Lesson 1 – LR1 Which term refers to the distance between an initial position and a final position? A.displacement B.distance C.motion D.speed

Lesson 1 – LR2 A.acceleration B.distance C.motion D.speed Which is the measure of how quickly the velocity of an object changes?

Lesson 1 – LR3 A.average speed B.displacement C.distance D.time On a speed-time graph, what does the x-axis show?

Lesson 1 - Now 1.You must use a reference point to describe an object’s motion. 2.An object that is accelerating must be speeding up. Do you agree or disagree?

Lesson 2 Reading Guide - KC How do different types of forces affect objects? What factors affect the way gravity acts on objects? How do balanced and unbalanced forces differ? Forces

Lesson 2 Reading Guide - Vocab force contact force noncontact force friction Forces gravity balanced forces unbalanced forcesunbalanced forces

Lesson 2-1 A.What are forces? 1.A(n) force is a push or a pull that one object exerts on another object. 2.A force has a size and a(n) direction. a.The length of a force arrow relates to the size of the force. b.The direction of a force arrow shows the direction of the force. What are forces?

3.The unit of force is the newton. 4.A force can change an object’s velocity, which is the speed and direction of an object, causing acceleration.

Lesson 2-2 B.Types of Forces 1.A(n) contact force is a push or a pull on one object by another object that is touching it. 2.Contact forces are also called mechanical forces. Types of Forces Steve Cole/Getty Images

Lesson A(n) noncontact force is a force that pushes or pulls an object without touching it. 4.Examples of noncontact forces include magnetism and gravity. Types of Forces (cont.)

Lesson 2-3 C.Friction 1.Friction is a contact force that resists the sliding motion between two objects that are touching. 2.The direction of the force of friction is opposite the direction of the motion. 3.Rougher surfaces produce greater friction than smoother surfaces do. Friction

Lesson 2-4 D.Gravity 1.The noncontact attractive force existing between all objects with mass is gravity. 2.The measure of the amount of gravity acting on an object is its weight. Gravity

Lesson The amount of gravitational force decreases as the distance between two objects increases; thus, an astronaut’s weight decreases as she or he moves away from Earth into space.. Gravity (cont.)

Lesson Gravity is also affected by mass. Mass is the amount of matter in an object. As the amount of mass increases, the force of gravity between two objects increases.

a.The effect of the force of gravity is most noticeable if one object is very massive. b.Although the force of gravity acts equally on two objects, the less massive object accelerates more quickly.

Lesson 2-5 E.Combining Forces 1.The net force is the sum of all forces acting on an object. a.When forces act in the same direction, you can add the forces together. b.If forces act in the opposite direction, add them just as you add positive and negative numbers. Combining Forces

Lesson 2-5 Combining Forces (cont.) When different forces act on an object in the same direction, you can find the net force by adding the forces together.

Lesson Forces are balanced or unbalanced. Combining Forces (cont.)

Lesson 2-5 a.If the net force acting on an object is 0 N, the forces acting on it are balanced forces. Combining Forces (cont.)

Lesson 2-5 b.Balanced forces do not affect the motion of an object. Combining Forces (cont.)

Lesson 2-5 c.Unbalanced forces are the result of a net force that does not equal zero that acts on an object. d.The motion of an object changes when unbalanced forces act on it.

Lesson 2 - VS Forces are pushes and pulls exerted by objects on each other. Contact forces occur when objects are touching. Noncontact forces act from a distance.

Lesson 2 - VS Gravity is a force of attraction between two objects. The amount of gravitational force depends on the mass of the objects and the distance between them.

Lesson 2 - VS Balanced forces do not affect motion. Unbalanced forces change motion.

Lesson 2 – LR1 Which is a measure of the force of gravity acting on an object? A.friction B.mass C.unbalanced force D.weight

Lesson 2 – LR2 A.friction B.net force C.balanced forces D.unbalanced forces Which term refers to the sum of the forces acting on an object?

Lesson 2 – LR3 A.balanced B.contact C.net D.noncontact Which force pushes or pulls an object without touching it?

Lesson 2 - Now 3.Objects must be in contact with one another to exert a force. 4.Gravity is a force that depends on the masses of two objects and the distance between them. Do you agree or disagree?

Lesson 3 Reading Guide - KC How do unbalanced forces affect an object’s motion? How are the acceleration, the net force, and the mass of an object related? What happens to an object when another object exerts a force on it? Newton’s Laws of Motion

Lesson 3 Reading Guide - Vocab inertia Newton’s first law of motion Newton’s second law of motion Newton’s third law of motion force pair Newton’s Laws of Motion

Lesson 3-1 Forces are measured in a unit called a newton (N), named after English scientist Isaac Newton, who studied the motion of objects. Newton summarized his findings in three laws of motion. Newton’s Laws

Lesson 3-2 The tendency of an object to resist a change in motion is called inertia.inertia Newton’s First Law inertia Science Use the tendency to resist a change in motion Common Use lack of action

Lesson 3-2 Newton’s first law of motion states that if the net force acting on an object is zero, the motion of the object does not change.Newton’s first law of motion Newton’s first law of motion is sometimes called the law of inertia. Newton’s First Law (cont.)

Lesson 3-2 When the forces acting on an object are balanced, the object is either at rest or moving with a constant velocity. Unbalanced forces can cause an object to accelerate or decelerate. Unbalanced forces can also cause an object to change direction. Newton’s First Law (cont.)

Lesson 3-2 Newton’s First Law (cont.) accelerate from Latin celer, means “swift”

Lesson 3-2 Newton’s First Law (cont.) If one force on an object is 5 N upward and the other is 10N downward, what is the object’s motion?

Lesson 3-3 Newton’s second law of motionNewton’s second law of motion states that the acceleration of an object is equal to the net force exerted on the object divided by the object’s mass. Newton’s Second Law of Motion

Lesson 3-3 The direction of acceleration is the same as the direction of the net force. Newton’s second law lets you predict what combination of force and mass you need to get the acceleration you need. Newton’s Second Law of Motion (cont.)

Lesson 3-3 How are the acceleration, the net force, and the mass of an object related? Newton’s Second Law of Motion (cont.)

Lesson 3-4 Newton’s third law of motion says that when one object exerts a force on a second object, the second object exerts a force of the same size, but in the opposite direction, on the first object.Newton’s third law of motion When two objects apply forces on each other, one of the forces is called the action force, and the other is called the reaction force. Newton’s Third Law

Lesson 3-4 Newton’s Third Law (cont.) What happens when one object exerts a force on a second object?

Lesson 3-4 When two objects exert forces on each other, the two forces are a force pair.force pair Force pairs are not the same as balanced forces. Balanced forces combine or cancel each other out because they act on the same object. Each force in a force pair acts on a different object. Newton’s Third Law (cont.)

Lesson 3-5 Newton’s laws do not apply to all motion in the universe, such as the motion of very tiny objects, such as atoms or electrons, or the motion of objects that approach the speed of light. You can often see the effects of all three of Newton’s laws at the same time. Newton’s Laws in Action

Lesson 3-5 Newton’s Laws in Action (cont.) DEX IMAGE/Getty Images Masterfile

Lesson 3 - VS Newton’s first law of motion states that the motion of an object remains constant unless acted on by an outside force. This also is called the law of inertia.

Lesson 3 - VS Newton’s second law of motion relates an object’s acceleration to its mass and the net force applied to the object.

Lesson 3 - VS Newton’s third law of motion states that for every action force, there is an equal but opposite reaction force. The two forces are called a force pair.

Lesson 3 – LR1 When balanced forces act on an object, the object is either moving with a constant velocity or _____. A.speeding up B.slowing down C.changing direction D.at rest

Lesson 3 – LR2 A.the direction of the action force B.the direction of the inertia C.the direction of the net force D.the direction of reaction force According to Newton’s second law of motion, the direction of acceleration is the same as which direction?

Lesson 3 – LR3 A.Newton’s first law of motion B.Newton’s second law of motion C.Newton’s third law of motion D.a force pair Which is also known as the law of inertia?

Lesson 3 - Now 5.All forces change the motion of objects. 6.The net force on an object is equal to the mass of the object times the acceleration of the object. Do you agree or disagree?

Chapter Review Menu Key Concept Summary Interactive Concept Map Chapter Review Standardized Test Practice

The BIG Idea Forces are pushes and pulls that may change the motion of an object. Balanced forces result in an object remaining at rest or moving at a constant speed. Unbalanced forces result in the acceleration of an object.

Key Concepts 1 An object’s motion depends on how it changes position. Motion can be described using speed, velocity, or acceleration. Speed is how fast an object moves. Velocity describes an object’s speed and the direction it moves. Acceleration describes the rate at which an object’s velocity changes. A graph can show you how either the displacement or the speed of an object changes over time. Lesson 1: Describing Motion

Key Concepts 2 Lesson 2: Forces A force is a push or pull on an object. Contact forces include friction and applied forces. Noncontact forces include gravity, electricity, and magnetism. Gravity is a force of attraction between any two objects. Gravitational force increases as the masses of the objects increase and decreases as the distance between the objects increases. Balanced forces acting on an object cause no change in the motion of the object. When unbalanced forces act on an object, the sum of the forces is not equal to zero. Unbalanced forces cause acceleration.

Key Concepts 3 Inertia is the tendency of an object to resist a change of motion Newton’s first law of motion states that an object will remain at rest or in constant straight-line motion unless unbalanced forces act on the object. Newton’s second law of motion states that the acceleration of an object increases as the force acting on it increases and decreases as the mass of the object increases. Newton’s third law of motion states that for every action force, there is an equal but opposite reaction force. The action-reaction forces are called a force pair. Lesson 3: Newton’s Laws of Motion

Chapter Review – MC1 A.acceleration B.reference point C.speed D.velocity To describe motion you need both direction and what?

Chapter Review – MC2 A.acceleration B.displacement C.speed D.velocity Which describes the distance an object moves divided by the time it took to move that distance?

Chapter Review – MC3 A.contact force B.friction C.net force D.noncontact force Which term refers to a push or a pull applied by one object to another object that is touching it?

Chapter Review – MC4 A.friction B.gravity C.inertia D.mass Which is a contact force that resists the sliding motion between two objects that are touching?

Chapter Review – MC5 A.force pair B.gravity C.inertia D.unbalanced forces Which term describes the tendency of an object to resist a change in motion?

Chapter Review – STP1 A.inertia B.mass C.motion D.weight Which changes when an unbalanced force acts on an object?

Chapter Review – STP2 A.acceleration B.displacement C.distance D.velocity Which is the speed and direction of an object’s motion?

Chapter Review – STP3 A.You pedal to speed up. B.You turn at constant speed. C.You coast to slow down. D.You pedal at constant speed. You are riding a bike. In which situation are the forces acting on the bike balanced?

Chapter Review – STP4 A.friction B.gravity C.inertia D.net force Which is a noncontact force that exists between all objects that have mass?

Chapter Review – STP5 A.action force B.force pair C.inertia D.reaction force When two objects exert forces on each other, the two forces are called what?