Question

An object is dropped from a height of 25 meters. At what velocity will it hit the ground?
7.0 meters/second
11 meters/second
22 meters/second
49 meters/second
70 meters/second

Answer 1

you can use the equations of motion for this question -

you know the initial velocity u u=0 because it is 'dropped')
you know the acceleration a (= g)
you know the distance s = 25m

so use the equation \[v ^{2}=u ^{2}+2as\]
to calculate v

Answer 2

v=sqrt(2gh)=22

Answer 3

it is valid only for vacuum