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

AI Thread Summary
Changing the reference point in potential energy calculations affects the values obtained but not the overall energy change. In this scenario, the gravitational potential energy (PE) of the trophy when held is calculated as 9.8 J using the height of 0.5 m. When the trophy falls to the athlete's toe, which is 0.03 m above the floor, the change in gravitational potential energy is approximately 9 J. The discussion also highlights that while gravitational potential energy is the primary focus, other forms of potential energy, such as electric and magnetic, exist. Understanding these concepts is crucial for solving energy-related problems in physics.
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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