# Homework Help: Determining Constants in Equataions

1. Oct 13, 2007

### BayernBlues

1. The problem statement, all variables and given/known data

In all the following problems state the variables or combination of variables
which should be plotted to check the suggested variation and state how the unknown
may be found ( through the slope and/or intercept of the best fitting straight line
y = m x + b.). Because you are not given any numerical data it is just required to
qualitatively describe you method of solution in few lines with schematic graphs.

here are a couple of examples:
The gas law for an ideal gas is PV = RT , P and T are measured variables, V is fixed and
known. Determine R.

The linear expansion of a solid is described by ℓ = ℓo ( 1 + α.Δt ) where ℓ and Δt are
measured variables, ℓo is constant but unknown. Determine α .

3. The attempt at a solution

For the first one:
An increase in T will yield an increase in P because V is a fixed value. P is therefore the dependent variable while T is the independent variable. R is the coefficient to T therefore it will be the slope when P vs T is graphed.

My question is mainly how would I go about problems like this or more complicated than this. When it gives you an equation, two measured values, and a third one which is supposed to be a constant like g. How would you determine the constant?