# Homework Help: Simple proportionality question

1. Mar 20, 2012

### hmvince

Hey guys, simple question really:
Given the equation
Code (Text):
v = (Gm/r)[SUP]1/2[/SUP]
Is it wrong to say
Code (Text):
v is inversely proportional to r
Or do you have to say
Code (Text):
v is inverslely proportional to r[SUP]1/2[/SUP]

2. Mar 20, 2012

### tiny-tim

hey hmvince!
yes!!!
you don't have to say "inverslely"!

3. Mar 21, 2012

### hmvince

I thought you did have to, cos if you dont it means v increases with r, instead of v decreases with r.
Do you mean to say this?:
v is directly proportional to r-1/2?

Looking at your number of posts and recognitions I dont mean to say you are wrong, just trying to figure it out for myself!

4. Mar 21, 2012

### tiny-tim

hi hmvince!

yes, it's always best to ask until you're sure

no point in losing even one mark in an exam by knowing the maths but not using the generally-accepted phrase!

you can say

v is proportional to r-1/2

or

v is inversely proportional to r1/2

or

v and r-1/2 are proportional

or

v and r1/2 are inversely proportional​

(and you don't need "directly", since it adds no information … but it isn't actually wrong)

5. Mar 21, 2012

Thankyou!