Practice Energy Calculations



Practice Energy Calculations

Useful Information:

• Formula to find electrical energy is: Energy = power x time

• Duke Power charges about 8¢ per kWh.

• 1 ton of coal produces an average of 2500 kWh of electricity.

• Each kWh of electricity generated from coal produces 1.5 lbs of CO2.

• 1 gallon of gasoline produces about 22 lbs of CO2 when burned.

1) Assume that the lights in your kitchen use 300 watts. How much energy and how much does it cost to leave the lights on 24 hours a day for a week if electricity is 8cents/kilowatt hour?

For a month (assume 30 days/month)?

For a year?

2) How much energy and how much money do you use to run your window air conditioner rated at 1500 watts continuously for the month of July (assume 8¢/kWh).

If you assume that coal was used to produce the electricity for your air conditioner, how much coal was burned to produce the electricity used?

How much CO2 was produced by the electricity used to run your air conditioner?

3) An average incandescent light bulb has a life expectancy of 1,000 hours. How much energy would a typical 60 watt bulb use in a lifetime, assuming it lasts for 1,000 hours?

At 8¢/kWh, how much would it cost over its lifetime?

4) A compact fluorescent bulb uses 15 watts and has a life expectancy of 10,000 hours. How much energy and how much would it cost to use a compact fluorescent for 10,000 hours?

5) If your car gets 20 miles per gallon (MPG), and you drive an average of 10,000 miles each year, how many gallons of gas do you use a year?

At $2.00 per gallon, how much will you spend on gasoline for the year?

If the combustion of each gallon of gasoline produces 22 lbs of CO2, how much CO2 does your car produce each year?

If you traded your car in & bought one that got 25 MPG, how much gasoline would you save in one year?

How much money would you save?

How much less CO2 would be emitted into the atmosphere from your improved car?

Practice Energy Calculations

Useful Information:

• Formula to find electrical energy is: Energy = power x time

• Duke Power charges about 8¢ per kWh.

• 1 ton of coal produces an average of 2500 kWh of electricity.

• Each kWh of electricity generated from coal produces 1.5 lbs of CO2.

• 1 gallon of gasoline produces about 22 lbs of CO2 when burned.

1) Assume that the lights in your kitchen use 300 watts. How much energy and how much does it cost to leave the lights on 24 hours a day for a week if electricity is 8cents/kilowatt hour?

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For a month (assume 30 days/month)?

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For a year?

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2) How much energy and how much money do you use to run your window air conditioner rated at 1500 watts continuously for the month of July (assume 8¢/kWh).

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If you assume that coal was used to produce the electricity for your air conditioner, how much coal was burned to produce the electricity used?

1 ton = 2,000 lbs.

2,000 lbs. of coal = 2500 kWh [pic]

How much CO2 was produced by the electricity used to run your air conditioner?

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3) An average incandescent light bulb has a life expectancy of 1,000 hours. How much energy would a typical 60 watt bulb use in a lifetime, assuming it lasts for 1,000 hours?

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At 8¢/kWh, how much would it cost over its lifetime?

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4) A compact fluorescent bulb uses 15 watts and has a life expectancy of 10,000 hours. How much energy and how much would it cost to use a compact fluorescent for 10,000 hours?

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5) If your car gets 20 miles per gallon (MPG), and you drive an average of 10,000 miles each year, how many gallons of gas do you use a year?

[pic]

At $2.00 per gallon, how much will you spend on gasoline for the year?

[pic]

If the combustion of each gallon of gasoline produces 22 lbs of CO2, how much CO2 does your car produce each year?

[pic]

If you traded your car in & bought one that got 25 MPG, how much gasoline would you save in one year?

[pic]

How much money would you save?

[pic]

How much less CO2 would be emitted into the atmosphere from your improved car?

[pic]

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100 gallons of gas/yr

$200 per year

2,200 lbs CO2/yr

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