## Another Formula for POWER

Mojojoey12
Posts: 4
Joined: Wed May 15, 2019 9:50 pm

### Another Formula for POWER

Hi,

I was just reviewing my diagnostic test and in one of the explanations it states that...
"Rearranging the units of J/s indicates that power can also be expressed as a constant force multiplied by a constant velocity (P = Fv)"

Can someone please explain the logic behind why power P=Fv ???? am I missing something? when I try to rearrange the units I get waaayy off

Thank you!
NS_Tutor_Mathias
Posts: 67
Joined: Sat Mar 30, 2019 8:39 pm

### Re: Another Formula for POWER

Code: Select all

``````P=W/t=Fv

units of v: m/s
units of F: N or kg*m/s^2

(m*s)*(kg*m/s^2)=kg*m^2/s^3

units of W: J or kg*m^2/s^2
units of t: s

kg*m^2/s^2/s = kg*m^2/s^3``````
If you're suspicious of the SI units for the Joule, just go back to the only physics formulas I ever remember:
F=ma
and
W=Fd

so

W=mad = (kg*m/s^2)*m= kg*m^2/s^2

I really recommend building these up a few times from just F=ma and transforming them all in SI units back and forth. The MCAT is heavy on unit analysis.
Mojojoey12
Posts: 4
Joined: Wed May 15, 2019 9:50 pm

### Re: Another Formula for POWER

WOW! I just realized what i messed up on.

Thank you so much!!!   