# How to write joules per metre squared per second

1. Nov 10, 2011

### autodidude

This was a question I had in another post, but the main topic was on a similar but different issue...

If I had the dimensions joules per metre squared per second (e.g. like for a solar panel), how would I write that?

I've been told
$$\frac{Js}{m^2}$$

But I get $$\frac{J}{m^2s}$$

Why is it this:
$$\frac{J}{1} \times \frac{s}{m^2}$$
And not:
$$\frac{J}{m^2} \times \frac{1}{s}$$

I'm grouping joules over metre squared together whereas everyone I've talked to does the first one - why? And am I wrong for saying 'per metre per second'? Should time come first? What is the convention here?

Thank you

2. Nov 10, 2011

### JHamm

If you mean that each second you are receiving 'x' joules of energy over each square meter then $\frac{J}{m^2 s}$ are the correct units.

3. Nov 10, 2011

### technician

I agree with JHamm... you have it correct J/m^2s not Js/m^2
It means Watts per square metre which makes sense when talking about solar panels.