posted by Josh .
A 84 kg runningback is running at 3.5 m/s. The running back is met by 152 kg defensive lineman. If the collision between the runningback and the defensive lineman results in both coming to a stop, find the speed(absolute value) that the defensive lineman was moving at.
so far no one is answering our questions. you should try conservation of momentum: m1v1 + m2v2=(m1+m2)vf then just solve for vf, your final velocity...just a suggestion in case you haven't tried it yet.
actually i think that's wrong, i think its only when they collide and one pushes the other. as result they move in the same direction