Question

17. A rock is thrown horizontally off a 62m high cliff. It lands 60m away from the cliff.Find the time the rock fell

Answer 1

3.56 s

Step-by-step explanation:

To find the time the rock fell, we can just analyze the vertical motion of the rock, which is a free fall motion. So we can use the suvat equation

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

where

s is the vertical displacement

u is the initial vertical velocity

a is the acceleration

t is the time

In this problem, taking downward as positive direction:

s = 62 m (height of the cliff)

u = 0 (the rock is thrown horizontally, so no vertical velocity)

`a=g=9.8 m/s^2` (acceleration of gravity)

Solving for t, we find

`t=\sqrt{(2s)/(a)}=\sqrt{(2(62))/(9.8)}=3.56 s`