1. Chapter 5 Review
Projectile Motion

2. Question 1
At what part of a path does a projectile have minimum speed?

3. Answer
At the top of its path

4. Question #2
A cannonball is launched horizontally from a tower. If the cannon has a barrel velocity of 60 m/s, where will the cannonball be 1 second later (∆x)?

5. Answer
60 m downrange

6. Question
In the absence of air resistance, at what other angle will a thrown ball go the same distance as one thrown at an angle of 75 degrees?

7. Answer
15 degrees

8. Question
A snowball rolls off the edge of a horizontal roof at a velocity of 3.0 m/s. What is the speed of the snowball, 1 second later? (solve for overall speed not vx or vy)

9. Answer
10.44 m/s

10. Question
The horizontal and vertical components of a projectile’s motion are _____

11. Answer
Independent

12. Question
A cannonball is launched from the ground at an angle of 30 degrees above the horizontal and a speed of 30 m/s. Ideally (no air resistance) the ball will land on the ground with a speed of?

13. Answer
30 m/s

14. Question
After a rock that is thrown straight up reaches the top of its path and is starting to fall back down, its acceleration is (neglecting air resistance)
Less than it was at the top
Greater than it was at the top
The same as it was at the top

15. Answer
The same as it was at the top (c)

16. Question
A ball is thrown straight upward at 10 m/s. Ideally (no air resistance), the ball will return to the thrower’s hand with a speed of…

17. Answer
10 m/s

18. Question
A projectile shot with an initial velocity of 51 m/s at an angle of 45 degrees follows a parabolic path and hits a stationary balloon at the top of its trajectory. With what speed does the projectile hit the balloon?

19. Answer
36 m/s

20. Question
A projectile launched horizontally hits the ground in 0.8 s. If it had been launched with a much higher speed in the same direction, it would have hit the ground (neglecting Earth’s curvature and air resistance) in…
More than 0.8 s
Less than 0.8 s
0.8 s

21. Answer
0.8 s (c)

22. Question
A cannon with a barrel velocity of 140 m/s launches a cannonball horizontally from a tower. Neglecting air resistance, how far vertically will the cannonball have fallen after 4 seconds?

23. Answer
80 m

24. Question
Helene the high jumper leaves the ground with a speed of 9.1 m/s at an angle of 75 degrees to the horizontal. If the bar is set at 4 m, does Helene clear the bar? (you need to tell me how high she jumps along with if she clears the bar or not)

25. Answer
No, y=3.86 m

26. Question
A projectile is fired horizontally in a vacuum. The projectile maintains its horizontal component of speed because it
Has no vertical component of speed to begin with
Is not acted on by any forces
The net force acting on it is zero
Is not acted on by any horizontal forces

27. Answer
Is not acted on by any horizontal forces (d)

28. Question
Jose can jump vertically 1 meter from his skateboard when it is at rest. When the skateboard is moving horizontally, Jose can jump
No higher
higher

29. Answer
No higher (a)

30. Question
At what launch angle will a ball travel the farthest distance in a vacuum?

31. Answer
45 degrees

32. Question
Tommy is playing a carnival game for which he must throw a football through a hoop in order to win. If the hoop is located a horizontal distance of 0.8 m from Tommy, and Tommy throws the ball with a speed of 20 m/s, taking 0.5 s to reach the hoop, at what angle must Tommy make his throw to win? (the hoop is located at the point of maximum height for the football)

33. Answer
85.4 degrees

34. Question
A ball is thrown into the air at some angle. At the very top of its path, its velocity is
Entirely vertical
There’s not enough information
Both vertical and horizontal
Entirely horizontal

35. Answer
Entirely horizontal (d)

36. Question
An object is dropped and falls freely to the ground with an acceleration of g. If it is thrown upward at an angle instead, its acceleration would be… O
Larger than g
g upward
g downward
None of the above

37. Answer
g downward (d)

38. Question
What is the resultant of a 3 unit vector and a 4 unit vector at right angles to each other (magnitude only)?

39. Answer
A 5 unit vector

40. Question
True or False: You throw a baseball at an upward angle into the air. The vertical distance between the baseball and an imaginary line tracing the upward angle into infinity is greater than the vertical distance the baseball would fall if it were dropped from rest and had been falling for the same amount of time.

41. Answer
False

42. Question
A baseball is hurled into the air at an angle of 30 degrees above the horizontal and lands on a target that is at the same level as that where the baseball started. The baseball will also land on the target if it is thrown at an angle of ____ degrees.

43. Answer
60 degrees

44. Question
In Chapter 2, you learned about “hang time”, the time a jumper’s feet are off the ground in a vertical jump. If the jumper runs horizontally and has the same vertical component of takeoff velocity, hang time will be…
No different
Decreased
Increased

45. Answer
No different (a)

46. Question
A package falls out of a helicopter that is traveling horizontally at 70 m/s. It falls into the water below 8.0 seconds later. Assuming no air resistance, what is the horizontal distance it travels while falling?

47. Answer
560 m

48. Question
A ball thrown in the air will never go as far as physics ideally would predict because…
One can never throw the ball fast enough
Gravity is acting
Air friction slows the ball
Ideally the ball would never land

49. Answer
Air friction slows the ball (c)

50. Question
At the instant a ball is thrown horizontally with a large force, an identical ball is dropped from the same height. Which ball hits the ground first?

51. Answer
Neither – they both hit the ground at the same time

52. Question
A cannonball is fired at some angle into the air. In the first second it moves 5 meters horizontally. Assuming it doesn’t hit the ground and air resistance is negligible, how far does it move horizontally in the next second?
More than 5 m
Less than 5 m
5 m
Not enough information

53. Answer
5 m

54. Question
Kyle throws a ball horizontally from the top of a building that is 5.0 m high. He hopes the ball will reach a swimming pool that is at the bottom of the building, 12.0 m horizontally from the edge of the building. If the ball is to reach the pool, with what initial speed must Kyle throw it with?

55. Answer
12.0 m/s

56. Question
A ball is thrown horizontally from the top of a tall cliff. Neglecting air drag, what vertical distance has the ball fallen 2.0 s later?

57. Answer
20 m