Posted by Jay on .
A 2 kg rock is released from rest at a height of 29 m. Ignore air resistance and determine the kinetic energy, gravitational potential energy, and total mechanical energy at each of the following heights;20m 15m 9m
* physics  bobpursley, Wednesday, November 17, 2010 at 9:32am
PE= mgh at any height.
KE at any height= InitialPEfinalPE
Total mech energy = KE+ PE
Please Can you explain how I can calculate kinetic energy if I don't know velocity I know formula mv^2/2 in this case I have to know the velocity.

physics 
bobpursley,
if KE = energy lost in PE
and you fell x distance, then
1/2 mv^2=mg*x and you calculate v from that.