tennis ball on Mars

2013-05-29 12:49 am
A tennis ball on Mars, where the acceleration due to
gravity is 0.379g and air resistance is negligible, is hit
directly upward and returns to the same level 8.5s later.

a) How high above its original point did the ball go?
b) How fast was it moving just after being hit?

回答 (1)

2013-05-29 2:23 am
✔ 最佳答案
(a) Use equation: s = vt - (1/2)at^2
with v = 0 m/s, a = -0.379g, t = 8.5/2 s = 4.25 s, s =?
hence, s = -(1/2).(-0.379g).(4.25^2) m = 34.23 m
[Take g = 10 m/s^2]

(b) Use v = u + at
with v = 0 m/s, a = -0.379g , t = 4.25 s, u =?
0 = u - 0.379g x 4.25
u = 16.1 m/s


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