# Proportionality Question

## Homework Statement

If P is proportional to q^2
and q is inversely proportional to r

Show that p is proportional to r^2

## Homework Equations

p = kq^2
q = c/r

where k and c are proportional constants

## The Attempt at a Solution

I'd say this is impossible. This is all the information given to me. This was found in an exam paper.

But even if we assume

k = c

p is not proportional to r^2.

-.-

Any ideas?

## Answers and Replies

dx
Homework Helper
Gold Member
You might have read the question wrong. If p ∝ q², and q ∝ 1/r, then p ∝ 1/r².

p=kq^2
q=c/r
therefore
p=k(c/r)^2
or
p=(kc^2)/r^2

So p should be inversely proportional to r^2, with the constant of kc^2.