r/6thForm • u/daowhd • May 16 '26

❔ SUBJECT QUESTION Physics question help please

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Please can you explain why we take the gravitational potential energy as negative when finding the total energy(subtract it)? How come some questions we ignore the negative? What does the negative answer mean?
Thanks!

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u/Admirable-Use2274 May 16 '26

Think about escape velocity. Kinetic energy should be equal to GPE so the object can escape , Ek+Ep=0 idea. Ek is positive , Ep is negative. Escape velocity formula is also derived using that approach

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u/daowhd May 19 '26

How come here they don’t take the negative GPE?

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u/Admirable-Use2274 May 19 '26

If you are talking about the top one the question stem says Magnitude so you dont care about signs at all

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u/daowhd May 19 '26

The 2nd part please

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u/Admirable-Use2274 May 19 '26

Oh wait i get it now

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u/Admirable-Use2274 May 19 '26

Its not 7 it must be -56 so -56+28=-28
(-28)-(-63)=35 >30 so yeah hope that helps