A 1200 kilogram car is traveling initially with a speed of 25.0 m/s in an easterly direction crashes into the rear end of a 9000 kilogram truck moving in the similar direction at 20.0 m/s. The velocity of the car right after the collision is 18.0 m/s to the east.
(a) Find the velocity of the truck right after the collision?
(b) Calculate how much mechanical energy is lost after the collision?