Answer
2100 J/K.
Work Step by Step
The initial kinetic energy of the cars is “lost” in this process, becoming “unusable” as it is turned into heat energy. Convert 85 km/h to 23.61 m/s.
$$\Delta S=\frac{Q}{t}=\frac{2(\frac{1}{2}mv^2)}{T}$$
$$\Delta S=\frac{(1100kg)(23.61m/s)^2}{(20+273)K}\approx 2100J/K$$
