Hi, can you please help me solve the following problem? It\'s notfrom a textbook

Question

Hi, can you please help me solve the following problem? It's notfrom a textbook, but we use the Giancoli Textbook as a resource.Thank you!

a) Suppose you jump up. Is the momentum of the Earth just beforeyou jumped different from the momentum of the Earth whileyou’re in the air?

1. No; the mass of the Earth is so large that the planet’schange in motion is imperceptible.
2. Yes; however, because of Earth’s much larger mass, itschange in momentum is much less than the change in yourmomentum.
3. Yes; as you jump, the Earth recoils, for the same reason that arifle recoils when firing a bullet, with a change in momentum thatis equal and opposite to your change of momentum.

b) After you land following the jump above in a), Earth’smomentum is
1. the same as it was before you jumped.
2. different from what it was before you jumped.

Explanation / Answer

a) 3. Yes; as you jump, the Earthrecoils, for the same reason that a rifle recoils when firing abullet, with a change in momentum that is equal and opposite toyour change of momentum. If we consider Earth to be an isolated system (during the shorttime interval that the people jump up, this approximation isappropriate), then momentum must be conserved. So the momentum ofEarth must be equal to and opposite that of the jumping people.Because of Earth's large inertial mass, however, there is noperceptible motion. b) 1. the same as it was before youjumped. It's impossible to change the momentum of an isolated system frominside the system.

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