Physics Help

SoSolid · 30 Apr 2006 at 09:17

Does anyone know what the base units of power are?

Inquisitor · 30 Apr 2006 at 09:20

Watts

SoSolid · 30 Apr 2006 at 09:22

I put that in my mid term exam and was marked wrong but I can't think what else it should be, so I'm starting to think I should have got that right!

Inquisitor · 30 Apr 2006 at 09:33

Maybe you misinterpreted the question?

JCBeastie · 30 Apr 2006 at 09:37

Joules

Arcade Fire · 30 Apr 2006 at 09:41

JCBeastie said:
Joules

No. One Watt is one Joule per second.

Joules are the unit of energy, or work, and power is the rate of doing work.

PhilthyPhil · 30 Apr 2006 at 09:41

kgm^2s^-3

Inquisitor · 30 Apr 2006 at 09:43

PhilthyPhil said:
kgm^2s^-3

PhilthyPhil · 30 Apr 2006 at 09:45

what's that supposed to mean? :confused:

Inquisitor · 30 Apr 2006 at 09:47

Well it's a rather long winded way of saying Watts isn't it?

Arcade Fire · 30 Apr 2006 at 09:47

It means that in SI units, the units of power are kilogram metres squared over seconds cubed.

Just for the record, the correct answer to the OP can be found in the second post, so you can safely ignore everything else in this thread as I predict that it will soon be filled with 'helpful' people coming in and giving the wrong answer and then an argument over who's right will ensue.

Inquisitor · 30 Apr 2006 at 09:49

Ahh, SI units, fair enough.

SaBBz · 30 Apr 2006 at 10:07

PhilthyPhil said:
kgm^2s^-3

Yep that's it. I guess base units must stand for SI units now then. I'd probably have said Watts too though, and I'm studying Physics at university

fatiain · 30 Apr 2006 at 10:16

Power is measured in Coleman Units aka mustard.

</ +1>

PhilthyPhil · 30 Apr 2006 at 10:18

The SI is just a unit system, so saying SI units is slightly ambiguous. Generally you would refer to ‘base units’ or ‘SI base units’ and ‘derived units’, Watts being a derived unit.

Arcade Fire · 30 Apr 2006 at 10:22

True.

Inquisitor · 30 Apr 2006 at 10:26

Ah, I get you now

SoSolid · 30 Apr 2006 at 10:58

PhilthyPhil said:
kgm^2s^-3

Yes you are absolutely correct, thinking about it now because a joule is not the bast unit of energy and power is equal to energy divided by time.

ArmyofHarmony · 30 Apr 2006 at 11:12

power = rate in change of energy = energy/time = joules/seconds

workdone(measured in joules) = force x distance
energy = ma x d = kgm(s^-2) x m=kg(m^2)(s^-2) = joules

so joules / seconds = kg(m^2)(s^-2) / s = kg(m^2)s(^-3)

Visage · 30 Apr 2006 at 11:22

Arcade Fire said:
It means that in SI units, the units of power are kilogram metres squared over seconds cubed.

Just for the record, the correct answer to the OP can be found in the second post, so you can safely ignore everything else in this thread as I predict that it will soon be filled with 'helpful' people coming in and giving the wrong answer and then an argument over who's right will ensue.

Ya think?