Question

A rock falls from rest off a cliff and hits the ground in 2 seconds. If there is no air resistance, determine the rock's velocity as the rock hits the ground.

Answer 1

Answer:

19.6m/s

Explanation:

A Rock falling off a cliff can be modeled as an object starting with  zero velocity moves with constant acceleration for certain period of time, for such motion following equation of motion can be used.

$v(t) = v_{0} +at$

here in our case $v_{0} =0$ because object starts off from rest and $a = g =9.8m/s^2$ is acceleration because of gravity ( Motion under gravity).

and of course t = 2 second.

Now by substituting all this information in equation of motion we get.

$v(2s) = 0+9.8m/s^2 *2s = 19.6m/s$

that would be the velocity of rock as it would hit the ground.

Note! We have assumed that there is no air resistance.

A rock falling off a cliff can be modeled as an object starting with zero velocity moves with constant acceleration for a certain period of time, for such motion following equation of motion can be used.

here in our case  because object starts off from rest and  is acceleration because of gravity ( Motion under gravity).

and of course t = 2 seconds.

Now by substituting all this information in equation of motion we get.

V = 19.6m/s

that would be the velocity of rock as it would hit the ground.

Note! We have assumed that there is no air resistance.