# How to convert the energy in Joules to mass in a metric done

1. Jul 24, 2011

### bpollard

any help would be appreciated. not sure where to start.

2. Jul 24, 2011

### Clever-Name

What do you mean convert energy in joules to mass in a metric done? I don't understand that statement.

What sort of system are you dealing with? Are you just trying to get a rest-mass for something given it's energy?

3. Jul 24, 2011

### bpollard

sorry, you are right.
Let me try again, can you help me convert energy (in Joules) to a mass (metric Tons)

4. Jul 24, 2011

### SammyS

Staff Emeritus
E = mc2 , I suppose.

5. Jul 24, 2011

### Clever-Name

It's also unclear what exactly you're dealing with.

Is this the energy of a moving object?

Or are you specifically looking for mass of an object which when completely converted into energy gives off a certain amount in Joules?

If it's the latter then you just use $E = mc^{2}$ which will give you the mass in kg, then you just need to find how many kg are in a metric ton.