1. Chapter 13
Motion and Forces

2. Ch 13 Sec 1: Gravity
Vocabulary gravity weight mass

3. Effects of Gravity All matter has mass Gravity = force of attraction
Due to mass of objects

4. Effects of Gravity Gravity pulls objects together
All objects exert gravity on other objects
Some objects too small of mass to notice

5. Effects of Gravity
Earth’s mass = pulls everything on planet to its center
You must apply force to overcome gravity any time you lift

6. Newton and Gravity Falling apple Law of universal gravitation
Concluded must be unbalanced force makes apple fall
Law of universal gravitation

7. Law of universal gravitation
Gravity depends on product (multiplication) of the masses of the objects
Gravity depends on distance between objects

8. Weight & Gravity Mass = amount of matter in object
Weight = amount of pull of gravity
Gravity = same everywhere on Earth
Gravity changes throughout universe depending on mass of nearest celestial body

9. Gravity & Static Objects
Static objects balance gravity by tension or compression

10. Ch 13 Section 2: Gravity and Motion
Terminal velocity
Free fall
Projectile motion

11. Gravity & Falling Objects
Gravity affects acceleration equally
Objects fall at same rate
Acceleration is dependent on mass and force
heavier objects = greater gravitational force
But heavier objects = harder to accelerate due to more mass

12. Gravity & Falling Objects
All falling objects on Earth accelerate at 9.8 m/s²

13. Air Resistance & Falling
Air resistance = force opposes gravity
Its magnitude depends on
Size
Shape
Speed of object

14. Air Resistance & Falling
Terminal velocity
falling speed when velocity no longer changes
Speed is same
Direction same

15. Air Resistance & Falling
Free Fall = only gravity acting on falling object
No air resistance
only possible in a vacuum

16. Projectile Motion
Two separate movements
Horizontal
vertical

17. Projectile Motion Horizontal movement Vertical Movement
Force gives object horizontal movement
Throwing a ball
Vertical Movement
Gravity pulls downward
Gravity only affects vertical movement

18. Orbiting Gravity provides centripetal force for an orbit
Centripetal = towards the center
Gravity = force to keep solar system in order

19. Ch 13 Sec 3: Newton’s Laws
Vocabulary inertia

20. Newton’s 1st Law
An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force

22. Newton’s 1st Law
Friction
Common force to stop object in motion

23. Newton’s 1st Law Sometimes called Law of Inertia
Inertia = at rest, stays at rest
Inertia & mass related
Smaller mass = less inertia
Larger mass = more inertia

24. Newton’s 2nd Law of Motion
The acceleration of an object depends on mass of the object and the amount of force applied

25. Newton’s 2nd Law of Motion
Acceleration depends on mass
more mass, with same force = less acceleration
Less mass, same force = greater acceleration

26. Newton’s 2nd Law of Motion
Acceleration depends on force
Less force, same mass= less acceleration
More force, same mass = greater acceleration

27. Newton’s 3rd Law of Motion
Whenever one object exerts a force on a second object, the second objects exert an equal and opposite force on the first

28. Newton’s 3rd Law of Motion
Action / Reaction
Forces act in pairs