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?

The following are the answers to the questions presented:

a. The joules of energy required to run a 100W light bulb for one day is 8640000J
b. The amount of coals that has to be burned to light that light bulb for one day is 0.96kg

The solution would be like this for this specific problem:

P=W/s→W=Pt=100W1day 24h/1day 3600s/1h=8640000J

W=30/100wm→m=100W/30w=100×8640000J/30×30×10in thepowerof6 J/kg=0.96kg

I am hoping that these answers have satisfied your queries and it will be able to help you in your endeavors, and if you would like, feel free to ask another question.