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Proportionality Question

  • Thread starter l46kok
  • Start date
  • #1
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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

  • #2
dx
Homework Helper
Gold Member
2,011
18
You might have read the question wrong. If p ∝ q², and q ∝ 1/r, then p ∝ 1/r².
 
  • #3
69
0
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.
 

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