1. Forces and Motion
Gravity

2. I) Gravity

3. A) Forces Make Things Move

4. 1) A force is a push or a pull

5. a) A force can make an object speed up, slow down, stop, or change direction.

6. b) Soccer players apply force to the ball

7. B) The Force of Gravity

8. 1) Gravity is the pull force of matter on other objects
1) Gravity is the pull force of matter on other objects. (No matter how large or small)

9. 2) Gravity is the force of Earth’s pull on us and everything toward its center

10. 3) Gravity holds the ocean and atmosphere close to earth’s surface

11. 4) The greater the mass of an object the greater its gravitational force

13. a) Two tennis balls are not pulled together since their mass is small.

14. b) The Moon is large enough that it’s gravity pulls on the oceans causing high and low tides

15. C) Mass and Gravity

16. 1) Mass is the amount of matter in an object

17. 2) Small objects are not massive enough to have noticeable gravitational pull on each other

18. a) Two bowling balls placed close to one another do not pull towards each other.

19. 3) Objects as massive as planets and moons have noticeable gravitational pull on objects

20. 4) The gravitational pull between two objects is equal, however the smaller one’s movement is affected more

21. a) Example: The sun gravity keeps the earth in orbit

22. 5) Some planets are so massive, they can make their star wobble, but the star still keeps the planet in orbit

23. D) Distance and Gravity

24. 1) The closer two objects are the stronger the gravitational pull, the farther apart two objects are the weaker the gravitational pull

25. 2) We feel earth’s gravity instead of the sun’s because we are closer to the earth than we are to the sun,

26. 3) As a Spacecraft travels further from earth it is affected by earth’s gravity less

27. But as the spacecraft travels towards Earth, Earth’s gravity pulls on it more

28. E) How Gravity is Measured

29. 1) Weight is a measure of pull of gravity on an object

30. 2) The Metric unit of measurement for force is the Newton

31. a) One Newton is the force needed to change the speed of 1kg (kilogram) by 1 m (meter) in 1 second

32. 3) The mass of an object stays the same no matter where it is, however the weight can change

33. a) Example: on the moon you would weigh 1/6 of your earth weight