Question

A box falls out of a stationary helicopter hovering 135 m above the ground. How long will it take to hit the ground?

Answer 1

We have the equation of motion $s = ut + \frac{1}{2} at^2$, where s is the displacement, a is the acceleration, u is the initial velocity and t is the time taken.

Here displacement = 135 m, Initial velocity = 0 m/s, acceleration = 9.81 $m/s^2$

Substituting

   $135 = 0*t+\frac{1}{2} *9.8*t^2\\ \\ 4.9t^2 =135\\ \\ t =5.25 seconds$

A box falls out of a stationary helicopter hovering 135 m above the ground will take 5.25 seconds to reach the ground.