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# An 70 kg quarterback jumps straight up in the air right before throwing a .43kg football horizontallly at 12?

An 70 kg quarterback jumps straight up in the air right before throwing a .43kg football horizontallly at 12 m/s.

how fast will he be moving backward just after releasing the ball? m/s

do you think it would be noticeable?

### 1 Answer

- Anonymous1 decade agoFavorite Answer
The Law of Conservation of Momentum says that the total momentum of the system must be conserved. The momentum in the horizontal direction started at zero, so the total must always be zero. The two momentums that must add to zero include that of the quarterback and that of the ball. Since momentum = mass X velocity and the two must be equal but opposite in direction, you can set the mass of the quarter back X his velocity = the mass of the football X its velocity. Solving for the quarterback's velocity it is equal to (mass of the ball) X (velocity of the ball)/(mass of the quarterback). Note that the velocity of the quarterback will be negative since the ball is positive.