Final answer:
When a rider hits a bump on a mountain bike, the spring in the shock absorber compresses to absorb the impact. The shock absorber then dissipates the energy as heat, preventing the spring from continuing to vibrate and bringing the bike back to a stable position.
Step-by-step explanation:
When a rider hits a bump on a mountain bike, the spring in the shock absorber compresses to absorb the impact. As the spring compresses, it stores potential energy. This potential energy is then converted into kinetic energy as the spring expands back to its original position, causing the bike to bounce up. However, the bouncing motion is damped by the shock absorber, which dissipates the energy as heat. The shock absorber consists of a piston that moves through a fluid-filled chamber. As the spring expands, the piston pushes against the fluid, which creates resistance and slows down the bouncing motion. This damping effect prevents the spring from continuing to vibrate and eventually brings the bike back to a stable position.