In a football game, a receiver is standing still, having just caught a pass. before he can move, a tackler, running at a velocity of +3.1 m/s, grabs him. the tackler holds onto the receiver, and the two move off together with a velocity of +1.6 m/s. the mass of the tackler is 115 kg. assuming that momentum is conserved, find the mass of the receiver.

Explanation:

The football players collide in a completely inelastic collision, in other words they have the same velocity after the collision, this velocity has a magnitude V=1.6m/s.

We need to use the conservation of momentum Law, the total momentum is the same before and after the collision, at the initial point the receiver does not have any speed

    (1)

We solve in order to find the receiver mass:

increase masses, decrease separation