Question

A hang glider dropped his cell phone from a height of 450 feet. How many seconds did it take for the cell phone to reach the ground?

Answer 1

t = 9.58 s

Explanation:

Given that,

The height from where the cell phone is dropped, h = 450 feet

We need to find the time for the cell phone to reach the ground. Let the time be t. Using second equation of kinematics to find it.

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

u is initial velocity, u = 0

a = g

So,

`h=(1)/(2)at^2\\\\t=\sqrt{(2h)/(g)} \\\\t=\sqrt{(2* 450)/(9.8)} \\\\t=9.58\ s`

So, it will take 9.58 seconds to reach the ground.