Question

A ball at rest falls from a platform above the ground. The ball falls freely and hits the ground 1.1 s later. What is the height of the platform? 5.4 m 5.9 m 10.8 m 11.9 m

Answer 1

Correct option is (b)

Step-by-step explanation:

Given a ball at rest falls from platform so initial velocity of the ball,

u =0

The ball hits the ground at time t = 1.1 s.

To calculate the height of the platform use equation of motion,

`h=ut+(1)/(2) at^(2)`

Here h is the height u is initial velocity of the ball t is time taken to hits the ground by ball and a is acceleration due to gravity and its .

Substitute the given values in above formula, we get

`h=0+(1)/(2) (9.8 m/s^(2))(1.1s)^(2)`

`h=5.9 m`

Thus, the height of platform is 5.9 m.