How Does Changing the Reference Point Affect the Potential Energy Calculation?

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Homework Help Overview

The discussion revolves around calculating the change in gravitational potential energy of a trophy as it falls from the hands of an athlete to the ground, with different reference points considered for the coordinate system. The problem involves understanding the concepts of potential energy and its dependence on the chosen reference point.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the formula for gravitational potential energy and how to apply it in different scenarios. Questions arise about differentiating between potential and kinetic energy, as well as the implications of changing the reference point for potential energy calculations.

Discussion Status

Some participants have provided calculations for potential energy and discussed the change in potential energy as the trophy falls. There is an ongoing exploration of different types of potential energy beyond gravitational potential energy.

Contextual Notes

The original poster expresses uncertainty about solving energy equations and differentiating between types of energy. The discussion includes repeated references to the same problem statement, indicating a focus on understanding rather than resolution.

Alaa Mahmoud
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Homework Statement



a trophy being shown off by a careless athlete slips from the athlete's hands and drops on his toe.Choosing floor level as the y=0 point of your coordinate system,estimate the change in gravitational potential energy of the trophy-Earth system as the trophy falls.Repeat the calculation,using the top of the athlete's head as the origin of the coordinate.
The trophy has a mass of 2 kg,and the top of a person's toe is about 0.03m above the floor.Also the trophy falls from a height of 0.5m.

Homework Equations



(? U)=(U final)-(U inetial)

The Attempt at a Solution


I'm not sure how to get started as I'm not good in solving equations of energ.
I don't know how can I differentiate between potential energy & kinetic energy ??
 
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Alaa Mahmoud said:

Homework Statement



a trophy being shown off by a careless athlete slips from the athlete's hands and drops on his toe.Choosing floor level as the y=0 point of your coordinate system,estimate the change in gravitational potential energy of the trophy-Earth system as the trophy falls.Repeat the calculation,using the top of the athlete's head as the origin of the coordinate.
The trophy has a mass of 2 kg,and the top of a person's toe is about 0.03m above the floor.Also the trophy falls from a height of 0.5m.

Do you know any eqn of potential energy of a body wrt Earth ?
 
cupid.callin said:
Do you know any eqn of potential energy of a body wrt Earth ?

Potential energy of gravity=mgy
 
Alaa Mahmoud said:
Potential energy of gravity=mgy

Yes. So What would be PE of system when trophy is in athlete's hands?
 
PE=mg(y initial)=2*9.8*0.5=9.8J right??
 
Alaa Mahmoud said:
PE=mg(y initial)=2*9.8*0.5=9.8J right??

Yes.
And similarly you can find the final PE ...
Then change will be ____ ?
 
OK thank you
the change in PE will be approximately 9 J
But is there any PE except gravitational PE?
 
Alaa Mahmoud said:
OK thank you
the change in PE will be approximately 9 J
But is there any PE except gravitational PE?

Yes. There are electric, magnetic etc
 
OK thanks a lot :)
 

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