How many Joules of energy are required to run a 100W light bulb for one day?
Burning coal yields about 30 x 10^6 J of energy per kilogram of coal burned. Assuming that the coal power plant is 30% efficient, how much coal has to be burned to light that light bulb for one day?

Question

How many Joules of energy are required to run a 100W light bulb for one day? 
Burning coal yields about 30 x 10^6 J of energy per kilogram of coal burned. Assuming that the coal power plant is 30% efficient, how much coal has to be burned to light that light bulb for one day?

jamesj · Answer

Nice.  You there?

anonymous · Answer

Yes, I'm here....

jamesj · Answer

Ok.  By definition power = change in work/energy over time.
P = W/t
Hence, how much energy does the bulb consume in one day?

jamesj · Answer

Work, W = (Power)*(Time)
or 
Energy, E = (Power)*(Time)

hence how much energy does the bulb consume?

jamesj · Answer

Watts = Joules/second.

The light bulb is rated as a 100 Watt bulb.

anonymous · Answer

Hi James, sorry I went offline, but thanks so much for your great help! Much appreciated!