Question

1 A stone falls from rest from the top of a high tower. Ignore
air resistance and take g = 10 m/s2.
a What is its velocity after
(i) 15,
(ii) 25,
(iii) 3s,
(iv) 5s?
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Answer 1

Answer:

The stone starts from rest, so initial velocity is 0. The stone falls with a constant acceleration of 10 m/s per second. Thus, in one second the velocity will have increased by 10 m/s from 0 m/s to 10 m/s. With constant acceleration, the average velocity over the time period is 1/2 the sum of the initial and final velocities or ½ (0 m/s + 10 m/s) or 5 m/s.

The distance traveled or displacement (s) is the average velocity times the time or

s = V x t = 5 m/s x 1 sec = 5 m