Stacy asked in Science & MathematicsPhysics · 7 years ago

# Needs Mega Help With My Physics Review (Help ASAP) Thank You c:?

10. A boy drops a ball from an observation tower. The ball hits the ground in 4.0 s. What is the ball's velocity at the time of impact?

0 m/s

39 m/s

16 m/s

78 m/s

14. You are running toward your friend at 5.0 m/s. He is running directly away from you, in a straight line, at 2.0 m/s. What is your velocity relative to him?

+3.0 m/s

7.0 m/s

3.0 m/s

+7.0 m/s

15. Which of the following is a vector describing how fast an object moves over a long time interval?

average speed

instantaneous velocity

average velocity

instantaneous speed

18. A car travels at uniform acceleration over a distance of 440.0 m. Its final velocity after 20.0 s is 33.0 m/s. What is its initial velocity?

0.0 m/s

11.0 m/s

22.0 m/s

8.7 m/s

19. Which of the following best describes the motion of a working gyroscope moving through space?

The gyroscope rotates, but does not translate.

The gyroscope both translates and rotates.

The gyroscope translates, but does not rotate.

The gyroscope neither translates nor rotates.

20. Karen runs sets in basketball practice. She starts from a line, runs 2.0 m, returns to the line, runs 4.0 m, returns to the line, runs 6.0 m, and on returning stops 1.0 m in front of the starting line. What is her distance and displacement?

distance = 23 m, displacement = +1 m

distance = +23 m, displacement = 1 m

distance = 1 m, displacement = +23 m

distance = +1 m, displacement = 23 m

25. How long does it take an acorn to hit the ground after dropping from the branch of a tree 25 m high? Remember that g = 9.8 m/s2.

1.0 s

2.3 s

22 s

5.1 s

Relevance
• 7 years ago

10. Velocity = acceleration * time = 4 * 9.81 = 39.24m/s

14. +3.0m/s (not sure)

15. Instantaneous velocity ( not sure)

18. s = 0.5 * (u+v) * t , where s=440, u = ?, v=33, t= 20

u = 11m/s

20. distance = 23 m, displacement = +1 m

25. s = ut + 0.5*a (t^2), where s=25, u =0, a=9.8, t?

25 = 0+ 4.9 (t^2)

t^2 = 5.102

t = 2.258 s

Hope it helped. :)

• None
Lv 7
7 years ago

To answer all questions except 15 and 19, see:

http://en.wikipedia.org/wiki/Equations_of_motion. All you need is in the section headed "SUVAT equations" and the calculations are rather simple arithmetic.

For more detail on derivations, see:

http://physics.info/motion-equations/

15. Average velocity (you are told it's a vector quantity. Average speed is a scalar quantity)

19. The gyroscope both translates and rotates.