Question

why we multiply and divide two quantities in physics
like F=ma, p=mv , pressure=f/a is there any special rule for this? anybody please suggest me.

Answer 1

Please be specific in your question, every formula in physics is accordance to the definition.
For example, the definition of pressure is force applied normal to the unit surface area, hence the formula is f/a.
That's the logic in all cases

Answer 2

in general. all these rules were concluded after practical expirements through which relations between some variables come.

Answer 3

we can not multiply any two r more quantities according to our wish....as f=ma force is a quantity which is due to some some rules and regulations.....so there will always be a rule for multiplication of physical quantities.......

Answer 4

u must see to it that the dimensions of quantities on either side of '=' match

Answer 5

there is no such rule in my opinion ,it all depends on the definition of the quantity and the cause behind its happening
for example pressure is the thrust or force acting per unit area hence it can be written as p=(f/a)
newton defined force as the rate of change of momentum....and on further simplification it turned as F=ma

Answer 6

We write these equations about a limited part of the universe which we call a "system". We assume this to be fixed and that nothing comes into it or leaves it. This is how we can do calculations about the conservation of things like momentum. As long as you describe what you are trying to express with your equations and stick with the above principle then, yes, you can use multiple relationships to learn and calculate new things.

So in your example, as long as your "m" is the same m in each equation - and your equations are valid - then you can substitute for one of them using the other equation. Rearranging that may produce mew interesting ideas. In many ways, this is what science is all about.

Answer 7

The units, or dimensions, of a quantity are the powers of mass, length, and time associated with it. For example units of a speed are length per time