Question

A body is dropped from a height of 80 m freely under gravity. Find the time taken by body to reach ground.
(g = 10 ms⁻²)

Answer 1

Time taken by body to reach the ground is 4 seconds.

Let initial velocity of body = u m/sec.

Let final velocity of body be v m/sec.

Distance traveled by body is =s m.

Time taken by body to reach ground is t seconds

Acceleration due to gravity is g =10 m/s^2 which act in downward direction.

According to newton's second equation of motion is s=ut+1/2gt^2

As body is dropped freely under influence of gravity hence initial velocity of body will be 0 that is u=0 /sec.

Substituting value in s=ut+1/2at^2 we have:--

s=80 m u=0 m/sec a=g=10 m/sec^2

80=0+1/2*10t^2

80=5t^2

t^2=16 so t=4 sec.

Hence time taken by body to reach ground is 4 seconds.