posted by Mark .
An apple falls from a tree (h = 9m). In the absence of air resistance,
how fast is it traveling when it strikes the ground?
potential energy is mgh = m(9.8)(9) = 88.2m where m is the mass of the apple.
given that there is no air resistance, all of these potential energy is converted to kinetic energy during the fall
i.e. Ep = Ek
so, Ek = 1/2mv^2 = Ep
1/2mv^2 = 88.2m
v^2 = 88.2m/0.5m ...so you can solve for velocity.
hope that helps..