Another Formula for POWER

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

Another Formula for POWER

Post by Mojojoey12 » Thu May 16, 2019 7:35 pm

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: 239
Joined: Sat Mar 30, 2019 8:39 pm

Re: Another Formula for POWER

Post by NS_Tutor_Mathias » Fri May 17, 2019 10:53 am

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

Post by Mojojoey12 » Sun May 19, 2019 9:01 pm

WOW! I just realized what i messed up on.

Thank you so much!!! :D :D :D
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