A 2,000 kg car is traveling at 20.0 m/s and then puts on the brakes and comes to a complete stop. The heat generated at the brakes due to stopping heats up the brakes. The mass of the brake system is 20.0 kg and it has a specific heat of 0.200 kcal/kg °C. What is the increase in the temperature of the brakes?

Question

Quizplus · Accepted Answer

The kinetic energy of the car is converted into heat energy in the brakes. The initial kinetic energy is (1/2)mv² = (1/2)(2000 kg)(20 m/s)² = 400,000 J. Converting this to kcal (1 kcal = 4184 J), we get approximately 95.6 kcal. Using Q = mcΔT, where m = 20 kg, c = 0.200 kcal/kg°C, and Q = 95.6 kcal, we solve for ΔT: ΔT = Q/(mc) = 95.6/(20*0.200) = 23.9 °C.

A 2,000 Kg Car Is Traveling at 20