An 80-kg quarterback jumps straight up in the air right before throwing a 0.43-kg football horizontally at 15 m/s . How fast will he be moving backward just after releasing the ball?

PLEASE SORT QUESTION BELOW

Sort the following quantities as known or unknown. Take the horizontal direction to be along the x axis.

mQ: the mass of the quarterback

mB: the mass of the football

(vQx)i: the horizontal velocity of quarterback before throwing the ball

(vBx)i: the horizontal velocity of football before being thrown

(vQx)f: the horizontal velocity of quarterback after throwing the ball

(vBx)f: the horizontal velocity of football after being thrown