1. How to Use This Presentation To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show”, or simply press F5 on the top row of your keyboard. To advance to the next slide click the left mouse button once. From the Chapter screen you can click on any section to go directly to that section’s presentation. Blank or “missing” areas of a slide will remain hidden until the left mouse button is clicked. You may exit the slide show at any time by pressing the Esc key Copyright © by Holt, Rinehart and Winston. All rights reserved.

2. Forces and Motion Module M: Chapter 2 Section 1: Gravity and Motion Section 2: Newton’s Laws of Motion Section 3: Momentum Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

3. Gravity and Motion Section 1 Bellringer Answer the following question in your science journal: If Wile E. Coyote and a boulder fall off a cliff at the same time, which do you think will hit the ground first? Would it matter if the cliff were very high or particularly low? How could Mr. Coyote slow down his fall? Copyright © by Holt, Rinehart and Winston. All rights reserved.

4. Gravity and Motion Section 1 Objectives Explain the effect of gravity and air resistance on falling objects. Explain why objects in orbit are in free fall and appear to be weightless. Describe how projectile motion is affected by gravity. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

5. Gravity and Motion Section 1 Gravity and Falling Objects Gravity and Acceleration Objects fall to the ground at the same rate because the acceleration due to gravity is the same for all objects. Acceleration Due to Gravity As shown on the next slide, for every second that an object falls, the object’s downward velocity increases by 9.8 m/s. Velocity of Falling Objects Velocity equals gravity times time. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

6. Falling Objects Accelerate at a Constant Rate Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved.

7. Gravity and Motion Section 1 Air Resistance and Falling Objects Acceleration Stops at Terminal Velocity As the speed of a falling object increases, air resistance increases. The upward force of air resistance continues to increase until it is equal to the downward force of gravity. The object then falls at a constant velocity called the terminal velocity. Free Fall Occurs When There Is No Air Resistance An object is in free fall only if gravity is pulling it down and no other forces are acting on it. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

8. Effects of Air Resistance on Falling Objects Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved.

9. Gravity and Motion Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved. Two Motions Combine to Cause Orbiting An object is orbiting when it is traveling around another object in space.When a spacecraft orbits Earth, it is moving forward. But the spacecraft is also in free fall toward Earth. Orbiting and Centripetal Force The unbalanced force that causes objects to move in a circular path is called a centripetal force. Gravity provides the centripetal force that keeps objects in orbit. Orbiting Objects Are in Free Fall End of Slide

10. How an Orbit Is Formed Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved.

11. Gravity and Motion Section 1 Copyright © by Holt, Rinehart and Winston. All rights reserved. Horizontal Motion When you throw a ball,your hand exerts a force on the ball that makes the ball move forward. This force gives the ball its horizontal motion,which is motion parallel to the ground. Vertical Motion A ball in your hand is prevented from falling by your hand. After you throw the ball,gravity pulls it downward and gives the ball vertical motion. Projectile Motion and Gravity End of Slide

12. Newton’s Laws of Motion Section 2 Bellringer Respond to the following question in your science journal: If you are sitting still in your seat on a bus that is traveling 100 km/h on a highway, is your body at rest or in motion? Explain your answer. Use a diagram if it will help make your answer clear. Copyright © by Holt, Rinehart and Winston. All rights reserved.

13. Newton’s Laws of Motion Section 2 Objectives Describe Newton ’s first law of motion,and explain how it relates to objects at rest and objects in motion. State Newton ’s second law of motion, and explain the relationship between force, mass, and acceleration. State Newton ’s third law of motion, and give examples of force pairs. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

14. Newton’s Laws of Motion Section 2 Newton’s First Law of Motion Copyright © by Holt, Rinehart and Winston. All rights reserved. Part 1: Objects at Rest Objects at rest will stay at rest unless they are acted on by an unbalanced force. Part 2: Objects in Motion Objects will continue to move forever with the same velocity unless an unbalanced force acts on them. Friction and Newton’s First Law Friction is an example of an unbalanced force that stops motion. End of Slide

15. Newton’s Laws of Motion Section 2 Newton’s First Law of Motion continued Inertia and Newton’s First Law Newton’s first law of motion is sometimes called the law of inertia. Inertia is the tendency of all objects to resist any change in motion. Mass and Inertia Mass is a measure of inertia. An object that has a small mass has less inertia than an object that has a large mass. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

16. Newton’s Laws of Motion Section 2 Newton’s Second Law of Motion Part 1: Acceleration Depends on Mass The acceleration of an object decreases as its mass increases. Its acceleration increases as its mass decreases. Part 2: Acceleration Depends on Force The acceleration of an object is always in the same direction as the force applied.The cart shown on the next slide moved forward because the push was in the forward direction. Expressing Newton’s Second Law Mathematically Acceleration equals force divided by mass. F = ma Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

17. Mass, Force, and Acceleration Section 2 Copyright © by Holt, Rinehart and Winston. All rights reserved.

18. Newton’s Laws of Motion Section 2 Newton’s Third Law of Motion Force Pairs Do Not Act on the Same Object A force is always exerted by one object on another object. This rule is true for action and reaction forces. However, action and reaction forces in a pair do not act on the same object. All Forces Act in Pairs—Action and Reaction Newton’s third law says that all forces act in pairs. The Effect of a Reaction Can Be Difficult to See The force of gravity pulling the Earth toward objects is an example. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

19. Momentum Section 3 Bellringer This section is about momentum. Make a list of five things that have momentum and a list of five things that don’t have momentum. What must you do to give an object momentum? What about removing momentum? What would happen to a hollow ball filled with water rolling across a table if you stopped it then moved your hand away quickly? Explain your answers in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

20. Momentum Section 3 Objectives Calculate the momentum of moving objects. Explain the law of conservation of momentum. Copyright © by Holt, Rinehart and Winston. All rights reserved. End of Slide

21. Momentum Section 3 Momentum, Mass and Velocity Copyright © by Holt, Rinehart and Winston. All rights reserved. What Is Momentum? The momentum of an object depends on the object ’s mass and velocity. Calculating Momentum Momentum equals mass times velocity. End of Slide

22. Momentum Section 3 The Law of Conservation of Momentum Copyright © by Holt, Rinehart and Winston. All rights reserved. Objects Sticking Together The mass of the combined objects is equal to the masses of the two objects added together. But, the combined objects move more slowly than either object did before the collision. Objects Bouncing Off Each Other When objects bounce off each other, momentum is usually transferred from one object to the other. The transfer of momentum causes the objects to move in different directions at different speeds. Conservation of Momentum and Newton’s Third Law Conservation of momentum can be explained by Newton’s third law of motion. End of Slide

23. Forces and Motion Chapter 6 Concept Map Copyright © by Holt, Rinehart and Winston. All rights reserved. Use the following terms to complete the concept map on the next slide: force, freefall, terminal velocity, gravity, air resistance, projectile motion.

24. Concept Map Chapter 6 Copyright © by Holt, Rinehart and Winston. All rights reserved. A B C D E F Force Gravity Free Fall Terminal Velocity Projectile Motion Air Resistance

25. Concept Map Chapter 6 Copyright © by Holt, Rinehart and Winston. All rights reserved.