Question

a stone is dropped from the edge of a roof: (a) how long does it take to fall 4.9 metre? (b) how fast does it move at the end of the Fall? (c) what will be its acceleration after 1 seconds and after 2 seconds?

Answer 1

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Answer 2

Answer:

h = 19.6 m

u = 0

h = u t + 1/2 g t * t

19.6   = 0 + 1/2 * 9.8 * t * t            as  g = 9.8 m/s/s

t = 2 sec.    it takes 2 sec.

acceleration is always the same : g = 9.8 m/sec

velocity / speed at t = 2 sec is  =  u + g  t  = 0 + 9.8 * 2 sec = 19.6 m/sec