# I What does this symbol represent?

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1. Feb 9, 2017

### Ian Baughman

In my nuclear engineering class we are looking at relativity right now. For one of our homework problems we have to derive an equation for a particle moving at relativistic speed showing the kinetic energy in terms of the particles momentum. In the answer they have a term mc and I have no idea what this represents. I can't find it in the book or online. I was wondering if somebody maybe knew what it meant?

2. Feb 9, 2017

### Orodruin

Staff Emeritus
Without proper context it is not possible to answer your question. Are we supposed to guess what the answer looks like and where this symbol appears?

3. Feb 9, 2017

### Ian Baughman

T = (p2c2+mo2c4)1/2-mcc2
I know:
p = momentum
T = Kinetic Energy
c = speed of light
mo = Rest mass​

I'm just confused on what mc represents.

4. Feb 10, 2017

### Staff: Mentor

I think that's just a typographical error, and $m_c$ should really be $m_0$ (the "rest mass", which also appears inside the parentheses). Or even a mechanical printing flaw that turned an "0" into a "c".

5. Feb 10, 2017

### Staff: Mentor

Based on the expression, it has to be m0. The expression subtracts the rest energy from the total energy.

6. Feb 10, 2017

### ChrisVer

As everyone mentioned above, this is a typo and was meant to be m0 (rest mass).
On the LHS of the equation you have T which is the "kinetic energy"... the kinetic energy would be equal to the total energy of your particle (E) minus the rest mass energy it has even when it's at rest (the m0).