# Mechanics DOUBT: WORK,ENERGY,POWER

When using the energy method to write an equation and find something, how do we decide on which side of the equation must loss/gain in kinetic/potential energy be written...hope this makes sense...coz everytime i get the final answer incorrect , due to writing them in the wrong side of the equation. for example; when gain in kinetic energy must be substracted from work done, i would have added it and this results in getting the final answer incorrect
(edited 1 year ago)
Original post by Marysa.15
When using the energy method to write an equation and find something, how do we decide on which side of the equation must loss/gain in kinetic/potential energy be written...hope this makes sense

initial KE + final PE - energy lost (e.g. work done by friction against the motion) + energy added (e.g. work done by the driving force) = final KE + final PE
Original post by Mocha Latte
initial KE + final PE - energy lost (e.g. work done by friction against the motion) + energy added (e.g. work done by the driving force) = final KE + final PE

why is final PE added in both sides???
Original post by Marysa.15
why is final PE added in both sides???

I'm assuming they meant initial PE on the left-hand-side because that's the correct formula.
Original post by notnek
i'm assuming they meant initial pe on the left-hand-side because that's the correct formula.

thank you very much
Original post by Notnek
I'm assuming they meant initial PE on the left-hand-side because that's the correct formula.

oh yeah sorry I mistyped!