You are Here: Home >< Maths

# M2 - GPE, KE, Friction formula?? Watch

1. Ive seen the formula Work done against friction = Loss in GPE– Gain in KE
used in a lot of mark schemes. How does this work and what questions do you use it for? Ive never seen it in the books.
2. (Original post by fpmaniac)
Ive seen the formula Work done against friction = Loss in GPE– Gain in KE
used in a lot of mark schemes. How does this work and what questions do you use it for? Ive never seen it in the books.
It's just conservation of energy. The total energy has to remain constant. So if both GPE and KE change, that is, their sum is not the same, the energy must have gone into work being done against friction since total energy is conserved.
3. (Original post by Zacken)
It's just conservation of energy. The total energy has to remain constant. So if both GPE and KE change, that is, their sum is not the same, the energy must have gone into work being done against friction since total energy is conserved.
So when theres friction you would use the above formula but when there isnt you would use GAIN IN KE = LOSS IN PE..
4. (Original post by fpmaniac)
So when theres friction you would use the above formula but when there isnt you would use GAIN IN KE = LOSS IN PE..
It depends on the question.

E.g. If you're moving up a slope then you'll be gaining GPE and losing KE. If there's no friction then Gain in GPE = Loss in KE.

As Zacken has said, try to understand the energy changes instead of relying on a formula.

TSR Support Team

We have a brilliant team of more than 60 Support Team members looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

This forum is supported by:
Updated: June 13, 2016
Today on TSR

...in schools

### I think I'm transgender AMA

Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• Poll
Useful resources

### Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

### How to use LaTex

Writing equations the easy way

### Study habits of A* students

Top tips from students who have already aced their exams

## Groups associated with this forum:

View associated groups
Discussions on TSR

• Latest
• ## See more of what you like on The Student Room

You can personalise what you see on TSR. Tell us a little about yourself to get started.

• The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.
{"found_math": false, "script_math_tex": 0, "script_math_asciimath": 0, "math_annotations": 0, "math_alttext": 0, "mathml": 0, "mathjax_tag": 0, "mathjax_inline_tex": 0, "mathjax_display_tex": 0, "mathjax_asciimath": 0, "img_math": 0, "codecogs_latex": 0, "wp_latex": 0, "mimetex.cgi": 0, "/images/math/codecogs": 0, "mathtex.cgi": 0, "katex": 0, "math-container": 0, "wp-katex-eq": 0, "align": 0, "equation": 0, "x-ck12": 0, "texerror": 0}