# Impossible question

1. Sep 22, 2009

### you_of_eh

From the following defining equations, determine the dimensions of the names physical quantities. Use L to represent the dimension length (distance), T to represent time and M to represent mass.

a) force, F: F=ma, (where m is mass and a is acceleration)
b) pressure, p: p=F/A, (where F is a force (see previous question) and A is an area)

-I can't even attempt to solve this question as I have no idea what the question is asking for.

2. Sep 22, 2009

### w3390

The question is asking you to write force and pressure all in terms of the units L, T, and M. So for example, velocity is L/T.

3. Sep 22, 2009

### you_of_eh

OK so..

a) would be.. F=M(deltaL/deltaT) ?
b) how can I define A using only L, M or T?

4. Sep 22, 2009

### w3390

No. Think about what you have written for force. That is saying that force is equal to mass times velocity. That is not correct. For part b, an area is simply two dimensions of length.

5. Sep 22, 2009

### you_of_eh

I still don't think I understand because this does not seem correct but..

a) F=M*d(L/T)/dT ?
b) p=M*d(L/T)/dT/L^2 ?