# Rearranging change in kinetic energy for mass

1. Jan 12, 2016

### Marts12

1. The problem statement, all variables and given/known data
I need to rearrange the change in kinetic energy equation for mass

2. Relevant equations
Change in Kinetic energy = 0.5mv^2-0.5mu^2

3. The attempt at a solution

I factorised the right hand side to give:

Change in kinetic energy = m(0.5v^2-0.5u^2)

Then:

m = Change in kinetic energy/(0.5v^2-0.5u^2)

Is this correct, any help would be greatly appreciated.

2. Jan 12, 2016

### BvU

Yes. But it would be better if you posted a more complete description of the exercise you are working on ...

3. Jan 12, 2016

### HallsofIvy

Staff Emeritus
Notice that you can factor out the "0.5" in both terms: $0.5v^2- 0.5u^2= 0.5(v^2- u^2)$ and, of course, that "0.5" in the denominator is the same as "2" in the numerator: $m= \frac{2 E_k}{v^2- u^2}$ where "Ek" is the kinetic energy. It's the same thing, just, perhaps, a little easier to read.