A 1,225-kg car traveling initially with a speed of 25.0 m/s in an easterly direction crashes into the rear end of a 8,500-kg truck moving in the same direction at 20.0 m/s. The velocity of the car right after the collision is 18.0 m/s to the east.
(a) What is the velocity of the truck right after the collision?
(b) How much mechanical energy is lost in the collision?