The body is released from a height of 100 m and falls freely.
The acceleration on the body is due to gravity and equal to 10 m/s and its initial velocity is 0
m/s.
Now we use the relation y = ut + (1/2) a*t^2 to find the time
taken to travel 10 m and 20 m.
For 10
m:
y = ut + (1/2) a*t^2
=> 10 =
0*t + (1/2)*10*t^2
=> 10 =
5t^2
=> t^2 = 2
=> t=
sqrt 2 s.
For 20 m:
y = ut + (1/2)
a*t^2
=> 20 = 0*t +
(1/2)*10*t^2
=> 20 =
5t^2
=> t^2 = 4
=> t= 2
s.
Therefore we see that the body takes sqrt 2 s to
fall 10 m and 2 s to fall 20m. The time taken to travel 20 m is not twice that
taken to travel 10 m as the body is accelerating.
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