ATAR Notes: Forum

VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Physics => Topic started by: kenhung123 on February 24, 2010, 02:39:05 pm

Title: Not really sure about these units
Post by: kenhung123 on February 24, 2010, 02:39:05 pm: Why is it that in gravitation g=N/kg not m/s^2?
Title: Re: Not really sure about these units
Post by: m@tty on February 24, 2010, 02:46:50 pm: $1N=1kgms^{-2}$
$1Nkg^{-1}=1kgms^{-2}kg^{-1}$
$\therefore 1 Nkg^{-1}=1 ms^{-2}$

They are the same.
Title: Re: Not really sure about these units
Post by: kenhung123 on February 24, 2010, 09:39:39 pm: Quote from: m@tty on February 24, 2010, 02:46:50 pm
$1N=1kgms^{-2}$
$1Nkg^{-1}=1kgms^{-2}kg^{-1}$
$\therefore 1 Nkg^{-1}=1 ms^{-2}$

They are the same.
So they can be used interchangeably? I can say g=10ms^-2 and a=10N/kg? because usually in answers they state g units as N/kg and a units as ms^-2
Title: Re: Not really sure about these units
Post by: Mao on February 24, 2010, 10:17:55 pm: Yes, just like how Ns is equivalent to kg m/s [momentum]
Title: Re: Not really sure about these units
Post by: /0 on February 24, 2010, 10:25:27 pm: $Nkg^{-1}$ is usually used when describing the gravitational field.

The gravitational field is 'force per unit mass', so the 'field' is defined so that $g = \frac{F}{m}$

Likewise, the electric field is 'force per unit charge', so the field is defined by $E = \frac{F}{q}$ , and the units are $NC^{-1}$

Just another way of looking at what 'g' means.