Question

A stone is dropped from the top of a cliff. It is seen to hit the ground below after 4.2 s. How high is the cliff?

Answer 1

@thomaster

Answer 2

we must first find the velocity of the stone after 4.2 seconds
v=u+gt
v=0+9.8(4.2)
final velocity of the object after 4.2 seconds is 41.16m/s
v^2=u^2+2gS
s=v^2-u^2/2g
s=(41.16)^2-(0)^2/2(9.8)
s=86.43 m
the height of the cliff is 86.44 metres above the ground