500
A 30kg rock is sitting on a cliff that is 10m high. Suddenly the rock starts to fall. The rock is falling at a velocity of 4m/s. Find the PE and KE for the rock when it is 4 meters off the ground
gpe = mgh
?30kg x 9.8m/s² x 10 m ?
gpe= 2940J??
ke = ½ mv²
?½ x 30kg x 64m/s
?ke = 960J
?me = ke + pe?
2940 J = 960J + pe
?-960 J = - 960J
?gpe = 1980J?