A 75 kg person slides from rest a distance of 5 m on a water slide, dropping through a vertical height of 2.5 m. (a) How much work does gravity do on the person? (b) What is the speed of the person at the bottom of the slide (assuming no friction)? (c) If there is a frictional force of 12 N, then what is the work done by the frictional force and what is the total work done?