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.

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.

here in our case because object starts off from rest and 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.

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.

yup its correct its: c) b b