Question: Gravitational Potential Energy in a Ball-Earth-Moon system?

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Discussion Overview

The discussion revolves around the gravitational potential energy and mechanical energy of a ball thrown upwards by a person on Earth, specifically examining the ball-Earth system and the ball-Earth-Moon system. Participants explore how energy changes during the ball's motion and the implications of including the Moon's gravitational influence.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests that the potential energy of the ball is converted into kinetic energy as it falls, indicating a decrease in potential energy in the ball-Earth system.
  • Another participant questions how the potential energy changes in the ball-Earth-Moon system, implying that the Moon's influence may alter the energy dynamics.
  • A later reply proposes a graphical representation of energy vs. time, describing a flat line for total energy, a peak in potential energy, and a corresponding change in kinetic energy as the ball is thrown and caught.
  • This same participant notes that the effect of the Moon on potential energy is minimal compared to that of the Earth due to the Earth's greater mass and proximity.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and clarity regarding the concepts, with some agreeing on the basic principles of energy conversion while others remain uncertain about the implications of the Moon's gravitational influence. The discussion does not reach a consensus on the overall impact of the Moon on the energy dynamics.

Contextual Notes

Some assumptions regarding the initial conditions of the ball's motion and the specific numerical values for energy calculations are not provided. The discussion also lacks a detailed exploration of the mathematical relationships involved in the energy transformations.

Who May Find This Useful

This discussion may be useful for students studying physics concepts related to gravitational potential energy, mechanical energy, and the effects of multiple gravitational bodies on energy systems.

centauri
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Hello, here's a questions I was wondering if any of you could solve. I don't have the exact numbers, but the scenario is this: a guy standing on the Earth throws a ball upwards and catches it a few seconds later.

How does would affect the potential energy and/or mechanical energy of the ball-Earth system? (Specifically, how might the graph of energy vs. time look like?)

Then, how would this affect the potential energy and/or mechanical energy of the ball-Earth-Moon system?

Any responses would be much appreciated.

Thanks.
 
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Potential energy of the ball will be utilized when it will fall .The energy we gave to ball was stored in form of potential energy converted into kinetic energy at the time of falling.
 
iqra toheed said:
Potential energy of the ball will be utilized when it will fall .The energy we gave to ball was stored in form of potential energy converted into kinetic energy at the time of falling.

So the potential energy of the ball will decrease in the ball-Earth system...but how about the Ball-Earth-Moon system?
 
Please...anyone, this is a concept I'm really struggling with.
 
centauri said:
How does would affect the potential energy and/or mechanical energy of the ball-Earth system? (Specifically, how might the graph of energy vs. time look like?)

I'm not 100% sure if the following is correct, but from the work I've done in my physics 210 class I believe it works as follows.

Ignoring the energy that put the ball into motion in the first place, the graph of the total energy is a flat line, the potential energy rises to a peak before falling back down, and the kinetic energy starts high,drops to zero, then rises again as the ball accelerates downward. Once the person catches the ball the K.E. is zero and the potential energy is back to its original value.

centauri said:
Then, how would this affect the potential energy and/or mechanical energy of the ball-Earth-Moon system?

It would look very similar to the above since the change in potential energy of the ball in the Moon's gravity is much smaller than the change in potential energy due to Earth's gravity. The Earth is both much more massive and much closer than the Moon is, so the change in potential energy as the ball goes up and comes down is much larger for the ball-Earth than for the ball-Moon.
 
Thank you so much! That seems much clearer to me now.
 

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