A 90kg bicycle and rider are traveling at 3m/s then start coasting down a hill. While coasting, the rider sees a branch lying across the trail right where the trail flattens out and skids to a stop. (Assume no friction until the rider starts breaking.) Required:
a. If the rider coasted 30m, and descended 9m in the process, what is his speed when he starts breaking?
b. How much heat does the braking generate?
c. If the specific heat of the tire's rubber is 2000J/kg K, 50g of tire are in thermal contact with the ground and 40% of the heat generated goes into the tire, how much does the tire heat up?
d. If it is not an emergency, why might pulsing your braking (compressing and releasing the brake several times while stopping) help prolong the life of your brakes?