Need Help with Two more quick physics questions.

Discussion in 'The Lounge' started by colbystephens, Mar 2, 2006.

1. colbystephens1 ton statusGMOTM Winner

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1. what are the units of a watt?
2. a certain car battery with a 12.0 v emf has an initial charge of 120 Amp Hours. Assuming that the potential across teh terminals stays constant ntil the battery is completely discharged, for how many hours can it deliver energy at the rate of 100W?

2. neverendingproject1/2 ton status

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watt=volts*amps

3. ryan22re1/2 ton status

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p=ir

watts = volts x amps

right?

4. colbystephens1 ton statusGMOTM Winner

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cool thanks. the answer in my book says 14.4 hours. seems like it should be exactly 14 tho. 12x120/100=14. any ideas?

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A watt is one Volt Amp, if that is what you are asking

14.4 hours, Don't quote me though

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I got 14.4 from my calculations

7. colbystephens1 ton statusGMOTM Winner

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can you explain the 14.4 - i end up with 14. i must be missing something pretty simple. oh crap. i just realized i can't multiply. 12x12=144, not 140. thanks, all.

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100W / 12Vdc = 8.333333333A
120 AH / 8.33333333 = 14.4Hrs

Make sense??

9. colbystephens1 ton statusGMOTM Winner

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yes, it makes sense now. i'm an idiot. and i can't multiply.

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