Question

A 1500-kg car is moving at 20.0 m/s. The driver brakes to a stop. The brakes cool off to the temperature of the surrounding air, which is nearly constant at 20.0° C. a. What is the total entropy change? b. Give a general explanation for what entropy is. c. Is there any way to modify this system to have zero change in entropy? Why or why not?

Answer 1

Explained

Step-by-step explanation:

Heat dissipated is Q=
`(1)/(2)mv^2=(1)/(2)*1500*20^2=300000` J

Temperature in Kelvin is 273+200=293 K

So
`\Delta S=(Q)/(T)=(300000)/(293)=1023.89J/K=1.02` kJ/K

b. Entropy is the measurement randomness of a system. It increases with increase in reversibility.

c. Heat generated is due to friction(Q) and if we could reduce this friction heat to zero, we can cause the system have zero change in entropy. This can be done with help of proper lubrication. Lubrication can make the system adiabatic.