Solve the three problems

in If a 5 kg object has a gravitational potential energy of 100 J with respect to a table top, how high above the table top is it? 6. A pendulum 3.0 m long with a 4.0 kg bob is pulled aside so that it is 1. 25 m above its lowest point and than released. What speed does it have at the lowest point in its swing? 7. An object was dropped from a cliff which was 50 m high. What speed did it have: (a) 40 m above the ground, (b) 25 m above the ground, and (c) just before it hit the ground