How do I calculate the power?

1. Nov 7, 2007

Inquiring_Mike

1. The problem statement, all variables and given/known data
We used a watt-hour meter in a lab, 400 revolutions of the dial = 1kWh. We measured the time for 10 revolutions of the dial ( in seconds).
How would I calculate the power?

Time for 10 revs = 146s

2. Relevant equations

3. The attempt at a solution
Power = (3600s/hr) / (146s) * (10/400) *1kWh = 0.62069 W ?

Last edited: Nov 7, 2007
2. Nov 7, 2007

Staff: Mentor

Does one mean Time for 10 revs = 146s or 146 revs in 10 s?

3. Nov 7, 2007

Inquiring_Mike

Sorry... fixed :)

4. Nov 7, 2007

Inquiring_Mike

... After some more thinking...I think it should be 0.62069 kW. Would this be correct?

5. Nov 7, 2007

Inquiring_Mike

Any help would be very much appreciated... :)

6. Nov 7, 2007

Staff: Mentor

Yes, but I calculate 0.6164 kW.

Take (1 kWh)/(400 revs)*(10 revs/ 146 s) * 3600 s/h = ______ kW.

The unit kWh is simply power (kW) * time (hours) = energy. 1 kW-s = 1 kJ, so 1 kWh = 3600 kJ.