11. A 5,000 kg train is traveling at a velocity of 100 m/s and hits another train. The two trains stick together, and the new velocity is 50 m/s. What is the
mass of the second train?
A. 5,000 kg
B. 15.000 kg
C. 10,000 kg
D. 8.000 kg

Two cannon balls weighing 18 kg and 24 kg are chained together and fired horizontally with a velocity of 165 m/s from the top of a 21-m wall. the chain breaks during the flight of the cannonballs and the 18-kg cannonball strikes the ground at t = 1.5 s, at a distance of 240 m from the foot of the wall, and 7 m to the right of the line of fire. determine the position of the other cannonball at that instant. neglect the resistance of the air.