Question

An 80kg quarterback jumps straight up in the air right before throwing a 0.43kg football horizontally at 15m/s . How fast will he be moving backward just after releasing the ball? (THIS IS NOT THE QUESTION THAT IS TO BE ANSWERED)

This is the question (THAT NEEDS TO BE ANSWERED):
Which of the following best describes why you can analyze this event using conservation of momentum?

a. The throwing action is quick enough that external forces may be ignored.

b. External forces don't act on the system during the jump.

c. Conservation of momentum is always the best way to analyze motion.

Answer 1

Answer:

The throwing action is quick enough that external forces may be ignored.

Explanation:

The law of conservation of momentum states that the sum of the initial and final momentum are equal. We know that when football is thrown, the  gravity pulls the quarterback and football downwards always to mean external force acts on the system. However, when the throwing action is quick, the external action may be ignored.