Why Is the Correct Answer mgh/4 in This Energy Problem?

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The discussion centers on a physics problem regarding potential energy, where the correct answer is mgh/4. The initial energy is calculated as mgh, and the final energy state is determined to be mgh/2. The key insight provided is the importance of considering the change in elevation of the center of mass when calculating potential energy changes. This clarification helps the original poster understand their mistake in the calculation. Ultimately, the correct approach leads to the conclusion that the answer is indeed mgh/4.
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Homework Statement


Hello All !

I have this question which I can't seem to get the correct ans to.. maybe I am missing something.. (Please refer to attachment)


Homework Equations



POtential energy = mass x g x h

The Attempt at a Solution



ok initial amt of energy = m x g x h

final energy state =( mgh/4 + mgh/4 )= mgh/ 2

so mgh - mgh/2 = mgh/2 (my ans)

apparently correct ans is mgh/4

help , pls ? thanks !
 

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Hi nish123, Welcome to Physics Forums.

When dealing with changes in potential energy, you want to consider the change in elevation of the center of mass.
 
ahh, got it!... thanks a ton
gneill and
ResscuedByMary

point i was missing was "When dealing with changes in potential energy, you want to consider the change in elevation of the center of mass."Thanks again !
 
thanks ResscuedByMary i now understand your explanation too...

"When dealing with changes in potential energy, you want to consider the change in elevation of the center of mass." was told by
gneill as above... thanks both !
 
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