A 79.0-kg fullback running east with a speed of 4.00 m/s is tackled by a 93.0-kg opponent running north with a speed of 3.00 m/s.

(a) Why does the tackle constitute a perfectly inelastic collision?

(b) Calculate the velocity of the players immediately after the tackle.
magnitude m/s
direction ° north of east

(c) Determine the mechanical energy that is lost as a result of the collision.
J

(d) Where did the lost energy go?