The Student Room Group

M2 Work help- is potential energy the same as work done against weight?

Question is in the title. I get that GPE is the same as work done by gravity and that the change in gpe+ work done by other forces = the change in ke, but I'm just wondering if there's a question about something moving up or hill or something, do I need to account for the work done by weight or is this included by GPE. I know this question is probably really stupid but its just one of those things I've never been properly explained
Reply 1
Original post by someone24
Question is in the title. I get that GPE is the same as work done by gravity and that the change in gpe+ work done by other forces = the change in ke, but I'm just wondering if there's a question about something moving up or hill or something, do I need to account for the work done by weight or is this included by GPE. I know this question is probably really stupid but its just one of those things I've never been properly explained


GPE is a different name for "work done against weight". They are precisely the same thing.
Reply 2
Cheers I just needed someone to say that, I dont know what it is about maths teacher trying to over explain everything
Reply 3
Original post by someone24
Cheers I just needed someone to say that, I dont know what it is about maths teacher trying to over explain everything


To be fair, the description is fairly obvious.

Work done against *force* is force multiplied by perpendicular distance.

So work done against weight is weight (mgmg) multiplied by perpendicular distance ((h)(h)): mghmgh.
Reply 4
I thought so, but the books keep refering them in differently in different scenarios, and my teacher kept referring it to work done by gravity, which I guess know I think about it they must be equal, I just needed some clarity on the subject, thanks anyway
Reply 5
Original post by someone24
I thought so, but the books keep refering them in differently in different scenarios, and my teacher kept referring it to work done by gravity, which I guess know I think about it they must be equal, I just needed some clarity on the subject, thanks anyway


No problem, glad I cleared it up. :smile:
Original post by someone24
Question is in the title. I get that GPE is the same as work done by gravity and that the change in gpe+ work done by other forces = the change in ke, but I'm just wondering if there's a question about something moving up or hill or something, do I need to account for the work done by weight or is this included by GPE. I know this question is probably really stupid but its just one of those things I've never been properly explained


Original post by Zacken
GPE is a different name for "work done against weight". They are precisely the same thing.


I got to the stage of rushing past the bit about "work done against gravity" and removed it from my later notes, just because students had the urge to include both of them in an equation.
Original post by tiny hobbit
I got to the stage of rushing past the bit about "work done against gravity" and removed it from my later notes, just because students had the urge to include both of them in an equation.


Any chance of having a look at these notes? I'm so screwed with M2 haha.

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