To practice problem-solving strategy 9.1 a strategy for conservation of momentum problems. 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?

Question

Physics

Lillian Ferguson

10 May, 18:48

To practice problem-solving strategy 9.1 a strategy for conservation of momentum problems. 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?

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Answers (1)

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Drake Maddox · Answer 1

Refer to the diagram shown below.

By definition momentum = mass * velocity.

Before throwing the ball:

The initial momentum is

P₁ = 0.

After throwing the ball:

Let u = the backward velocity of the quarterback.

The momentum is

P₂ = (0.43 kg) * (15 m/s) + (80 kg) * ( - u m/s)

Conservation of momentum requires that

P₂ = P₁

6.45 - 80u = 0

u = 6.45/80 = 0.0806 m/s

Answer: 0.08 m/s backward