2. A boxer can punch a heavy bag for more than an hour without tiring but will tire more quickly when boxing with an opponent for a few minutes. Why? (Hint: When the boxers punches are aimed at the...

2. A boxer can punch a heavy bag for more than an hour without tiring but will tire more quickly when boxing with an opponent for a few minutes. Why? (Hint: When the boxer’s punches are aimed at the bag, what supplies the impulse to stop them? When aimed at the opponent, what (or who) supplies the impulse to stop the punches that are missed?)