A joule is an amount of energy, and a watt is a rate of using energy, defined as 1 W = 1 J / s. How many joules of energy are required to run a 100 W light bulb for one day?

Coal has about 30E6 J of energy per kg, but a power plant can only use 30% of this energy to make electricity (i. e., it is 30% efficient). How many kilograms of coal have to be burned to light a 100 W light bulb for one day?

Question

Cherish Ho

Physics

5 October, 07:20

A joule is an amount of energy, and a watt is a rate of using energy, defined as 1 W = 1 J / s. How many joules of energy are required to run a 100 W light bulb for one day?

Coal has about 30E6 J of energy per kg, but a power plant can only use 30% of this energy to make electricity (i. e., it is 30% efficient). How many kilograms of coal have to be burned to light a 100 W light bulb for one day?

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Answers (1)

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Jaelyn Cook · Answer 1

How many joules of energy are required to run a 100 W light bulb for one day?

A 100 joules B 100 W * 24 hr joules C 100 W * 24 hr * 60 min∕hr joules D 100 W * 24 hr * 60 min∕hr * 60 s∕min joules