Question
Tue March 25, 2014 By: Amber Khan

A stone is dropped from a cliff. Its speed after it has fallen 400m is ????

Expert Reply
Wed March 26, 2014
Equation of motion for a free falling body is,
 
v2 = u2 + 2gs  (a = g)  
 
Given:
s = 400 m
u = 0 m/s
g = 9.8 m/s2
v = ?
 
v2 = 0 + 2 x 9.8 x 400
v2 = 7840
v = 88.54 m/s
 
Hence, speed of the stone after it has fallen 400m is 88.54 m/s.
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