1. If your pen falls off your desk does it accelerate? If I drop a pen, what is its initial speed? How fast is it going just before it hits the ground? ZERO NOT-ZERO

2. When something falls does its speed keep changing? Would you catch a baseball sized rock dropped from 1 meter above you? From 1,000 m above you? NO, the longer it falls the faster it gets

3. Gravity accelerates ALL objects in free fall at 9.80 m/s 2 If gravity is the only force acting on an object (no wind resistance etc…)

4. 1 kg and 5 kg hunks of lead are dropped from a building Which hits the ground first?

5. If they both accelerate at 9.8 m/s 2 they hit at the same time!!!

6. But does this really happen??? Do heavy object fall at the same rate as light ones???

7. Say 2 - one pound magnets were dropped. They would fall at the same rate. 1lb

8. What would happen if on the way down they stuck together. Now it is twice as heavy 1lb

9. Objects accelerate the same NO matter the mass? If I drop a rock and piece of paper will they fall at the same rate?

10. Why don’t all things fall at the same rate on earth Air resistance

11. If we could drop stuff in an environment without air we could test this theory.

12. Apple and a feather dropped in a vacuum

13. Gravity accelerates objects in free fall at g = 9.80 m/s 2 Should g be positive or negative?

14. Gravity accelerates objects in free fall at g = 9.80 m/s 2 For discussion purposes we will just round that to 10. But in labs and calculations use the real number

15. Time Falling (s) Instantaneous Velocity (m/s) 0 Freefall speed of objects dropped from rest 0 1 -9.8 -10 2 -19.6 -20 3 -29.4 -30 t -9.8t -10t

16. A penny is dropped from the top of the empire states building. ABOUT how fast is it going: 4 seconds after its release? 8.8 seconds after its release?

17. What would the velocity of an object in freefall look like graphed What is the initial acceleration when it was at rest?

18. 0s 1s 2s 3s 4s 0 m/s -10 m/s -20 m/s -30 m/s -40 m/s What are the velocities for a rock dropped from rest? Are these Average Velocity or Instantaneous Velocity

19. 0s 1s 2s 3s 4s -30 m/s -20 m/s -10 m/s 0 m/s -40 m/s What is the average velocity during the first second of freefall? How far did it go?

20. 0s 1s 2s 3s 4s -30 m/s -20 m/s -10 m/s 0 m/s -40 m/s How far did the rock fall after 2 seconds. etc.... What is the average velocity after 2 second of freefall? How far did it go? etc....3,4,

21. 0s 1s 2s 3s 4s 30 m/s 20 m/s 10 m/s 0 m/s 40 m/s How far does the rock fall EACH SECOND -5 m -15 m -25 m = -35 m -5 m -20 m -45 m 80 m

22. 0s 1s 2s 3s 4s 30 m/s 20 m/s 10 m/s 0 m/s 40 m/s -5 m -15 m -25 m = -35 m -5 m -20 m -45 m 80 m Why does the distance traveled EACH second increase?

23. A motion diagram of a falling ball (.5 second intervals)

24. Distance fallen changes with t 2

25. How much does the velocity of an object increase each second of fall? How much does the Displacement of an object increase each second of fall?

26. v = gt  y = gt 2 2

27. If you drop a rock, after 9.5 seconds? What is its velocity? What is its displacement (how far has it fallen)? What is the average velocity?

28. Freefall WS or

29. You are standing on a bridge and drop a rock. You hear it hit 6.8 seconds later. How high are you above the ground? what do I KNOW, what can I find?

30. Throwing downward v1v1 g Will the object speed up or slow down? What are the signs on v 1 and g?

31. If you Throw a rock down at 15 m/s, after 9.5 seconds? What is its velocity? What is its average velocity since being dropped? What is its displacement?

32. Throwing upward vovo g Will the object speed up or slow down? What are the signs on v 1 and g?

33. If I toss a rock upwards at 30 m/s, what will happen to its vertical velocity? 1s 2s 3s 4s 5s 6s 7s 30 m/s 20 m/s 10 m/s 0 m/s 40 m/s

34. How far above your hand will the rock be after traveling 1 second? 1s 2s 3s 4s 5s 6s 7s 30 m/s 20 m/s 10 m/s 0 m/s 40 m/s 2 seconds?

35. A rock is fired up at 53 m/s. What will its velocity be 2.0 seconds after being launched. What is its velocity? How high will it be? of equations v 1 + v 2 2 v = of equations xx v = tt v 2 -v 1 a = tt

36. A rock is fired up at 53 m/s. What will its velocity be 6.0 seconds after being launched. of equations v 1 + v 2 2 v = of equations xx v = tt v 2 -v 1 a = tt What is its velocity? How high will it be?

37. What do you know about an object when it reaches it’s highest point? 1s 2s 3s 4s 5s 6s 7s 30 m/s 20 m/s 10 m/s 0 m/s 40 m/s How high did this rock go??

38. If an object is launched from the ground. Compare the time going up to the time going down. 1s 2s 3s 4s 5s 6s 30 m/s 20 m/s 10 m/s 0 m/s What about the total time in the air. An object reaches the highest point when gravity slows it to a stop. Afterwards it takes the same time to fall back down.

39. If an object is launched from the ground. When it hits the ground again. Notice its speed-- 1s 2s 3s 4s 5s 6s 30 m/s 20 m/s 10 m/s 0 m/s What does this tell you about shooting a gun into the air? The speed is the same as when it left. Is the velocity??

40. v top = 0 m/s 1s 2s 3s 4s 5s 6s 30 m/s 20 m/s 10 m/s 0 m/s If the ground is level, its speed when it hits the ground is the same as when it was shot t up = t down t air = 2 t up

41. What is the acceleration here? 1s 2s 3s 4s 5s 6s 30 m/s 20 m/s 10 m/s 0 m/s

42. For an object thrown upward Where is the highest point? What is its acceleration then?

43. Key things to remember about this. 1s 2s 3s 4s 5s 6s 30 m/s 20 m/s 10 m/s 0 m/s The speed at the highest point is…. The speed when it reaches the ground again is… The time it takes to fall back down is equal to…. The time it takes to reach its highest point is _____ Of the total round trip time

44. If you throw a rock upward at 44 m/s. How long does it take to reach its highest point? How long after it hits the highest point does it take to reach your hand again? Total round trip time? What was its velocity when it hit your hand again? of equations v 1 + v 2 2 v = of equations xx v = tt v 2 -v 1 a = tt

45. A bullet is fired upward at 140 m/s. What is the time going up? How high did it go? How long was it in the air? What is the average velocity on the trip up? of equations v 1 + v 2 2 v = of equations xx v = tt v 2 -v 1 a = tt

46. If you shoot a golf ball straight up and it takes 10.0 s to hit the ground again... of equations v 1 + v 2 2 v = of equations xx v = tt v 2 -v 1 a = tt How long was it traveling upward? How high did it go? What was its velocity when it hit the ground? What was its velocity when it was shot?

47. A rock is dropped from a building, After 3 seconds, another identical rock is dropped from the same spot. What happens to the distance between the rocks while both are in free fall? ?