Two freight trains, each of mass 5 X 106 kilograms (5000 metric tons) travel in opposite directions on the same track with equal speeds of 42 meters/second (about 100 miles/hour). They collide head on and come to rest.
a) Calculate in milligrams the kinetic energy for each train (1/2)mv2 before the collision (1 milligram= 10-3 gram= 10-6 kilogram
b) After the collision the mass of the trains plus the mass of the track of the roadbed has increased by what number of milligrams?