Question

Sam is riding his bike in the park when he sees a soccer ball rolling toward him. He applies his brakes to slow down. Once he stops, he notices that the tires on his bike became warmer after he applied the brakes. Why did the tires on Sam's bike become warmer as he applies the brakes on his bike?

Answer 1

When Sam presses the brake lever, a pair of rubber shoes  clamps onto the metal inner rim of the front and back wheels. As the brake shoes rub  against the wheels, friction is caused and  the kinetic energy possessed by the vehicle is converted into heat which slows down the vehicle.