Which statement about brakes is true?

Which statement about brakes is true?

• A. Heavier or faster vehicles require more heat to stop
• B. Brakes generate less heat when heavy
• C. Heat is not a factor in stopping
• D. Brakes always stay cool

Answer: (A)

Brakes convert the vehicle’s kinetic energy into heat energy to slow and stop. The amount of energy that must be dissipated grows with mass and speed: kinetic energy is 1/2 m v^2, so heavier vehicles carry more energy and faster speeds increase energy even more. That means heavier or faster vehicles require more heat to be generated by the brakes to remove that energy and bring the vehicle to a stop. If the brakes can’t get rid of heat quickly enough, braking performance drops, a problem known as brake fade. So the true statement is that heavier or faster vehicles require more heat to stop. Brakes do heat up with use, and heat is a crucial factor in stopping, while they do not generate less heat when heavier.

Brakes convert the vehicle’s kinetic energy into heat energy to slow and stop. The amount of energy that must be dissipated grows with mass and speed: kinetic energy is 1/2 m v^2, so heavier vehicles carry more energy and faster speeds increase energy even more. That means heavier or faster vehicles require more heat to be generated by the brakes to remove that energy and bring the vehicle to a stop. If the brakes can’t get rid of heat quickly enough, braking performance drops, a problem known as brake fade. So the true statement is that heavier or faster vehicles require more heat to stop. Brakes do heat up with use, and heat is a crucial factor in stopping, while they do not generate less heat when heavier.