# physics

• Jun 20th 2007, 01:22 PM
cruzangyal
physics
You are told that the volume of a sphere is given by V=pie d3/4, where V is the volume and d is the diameter of the sphere. Is this equation dimensionally correct? Use SI unit analysis to find out.:confused: :confused:
• Jun 20th 2007, 01:26 PM
ppyvabw
well the dimension of d is length. [L]

3/4 and pi are dimensionless so the dimension of 3/4d^3 is [L]^3 which is the dimensions of volume.
• Jun 20th 2007, 02:04 PM
CaptainBlack
Quote:

Originally Posted by cruzangyal
You are told that the volume of a sphere is given by V=pie d3/4, where V is the volume and d is the diameter of the sphere. Is this equation dimensionally correct? Use SI unit analysis to find out.:confused: :confused:

Please clarify the purported formula, do you mean:

$
V=\pi d^3/4
$

which is dimensionally OK, or:

$
V=\pi d~\frac{3}{4}
$

which is not.

RonL
• Jun 20th 2007, 03:45 PM
ppyvabw
Yeah, I missed that

if its d, then its wrong

if its d^3 then its fine.
• Jun 21st 2007, 08:46 AM
John 5
Quote:

Originally Posted by CaptainBlack
Please clarify the purported formula, do you mean:

$
V=\pi d^3/4
$

I think she meant this one.