# Deriving Forumlas

#### DDS

I jsut have a quick question. I know that in physics and any other math, you can short cut your way if you know various relationships and thus you can derive various forumlas from a few simple ones. Is there any trick to doing this or an easier way, because i have never really been exceptionally well at it but i could always squeeze by.

If anyone knows any methods or tricks is it possible to let me know

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#### NateTG

Homework Helper
There are some notions about what formulae for certain types of relationships look like - proportional, inversely proportional, geometric, and so on. The general problem of translating a relationship into a nice expression is very difficult. It eventually does lead to very complicated formulae for things like QM.

#### The Bob

DDS said:
If anyone knows any methods or tricks is it possible to let me know
Try here for converting units (which is sort of the same think. You do have to construct the equation yourself). For other thinks it takes understanding of what you are doing and quiet a bit of maths. e.g trapiezum rule in maths needs the knowledge of calculus so that you can see how to use the area of a trapiezum to work out the rule with different 'heights'.

What sort of relationships/forumulae are you on about?

The Bob (2004 ©)

#### Chi Meson

Homework Helper
One trick I teach my students:
Often you will have two formulas with a common variable. If you solve both formulas for that variable, and then set them equal to each other, then that variable goes away. This is handy if you trying to figure out a problem where one seemingly important variable is always unknown.

#### brewnog

Gold Member
I suppose dimensional analysis helps here too.

The units of both sides of your equation (when expressed in their basic terms) should always be the same. You can often use this as a guide.

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