In an American football game, a 90.4 kilogram fullback running east with a speed of 5.07 m/s is tackled by a 94.0 kilogram opponent running north with a speed of 2.99 m/s.
(a) If the collision is perfectly inelastic, obtain the speed and direction of players just after the tackle.
(b) Obtain the mechanical energy lost as a result of the collision.