1. Two cars, each with a mass of 6000 kg, hit head on each traveling at 80 km=h. Estimate the increase in internal energy absorbed by the materials in each car.
2. A 6500-kg car is traveling at 90 km=h and suddenly brakes to a stop. If the four brake disks absorb all the energy, estimate the maximum increase in temperature of those disks, assuming the disks absorb the energy equally. The 0.7-cm-thick, 30-cm-diameter disks are made of steel. Use rsteel ¼ 7850 kg=m3 and ðcpÞsteel ¼ 0:5 kJ=kg·-C.