A6 kilogram concrete block is dropped from the top of a tall building. the block has fallen a distance of 55 meters and has a speed of 30 meters per second when it hits the ground. a. at the instant the block was released, what was its gravitational potential energy? b. calculate the kinetic energy of the block at the point of impact. c. how much mechanical energy was "lost" by the block as it fell? d. explain what happened to the mechanical energy that was "lost" by the block.