Free Printable Energy Efficiency Calculations

1.

A car uses 100 J of gasoline. 83 J are turned into mechanical energy. How much should be turned into heat?

a)

7 J

b)

17 J

c)

83 J

d)

100 J

2.

What does this equation mean? $\frac{useful\ output}{input}\ \times\ 100\%$

a)

Efficiency is the fraction of output energy that is useful, compare to how much energy you put in.

b)

Nothing, it's just math.

c)

Efficiency compares what useful energy you get out to how much you have to put in.

d)

Efficiency compares how much you put in to how much you get out, whether it is the type you want or not.

3.

A TV uses 200 J of electricity and transforms it into 125 J of sound and light and 75 J of heat. How efficient is it?

a)

62.5%

b)

.625%

c)

37.5%

d)

.375%

4.

My dog likes to run and bark. If he eats 1000 J of food, and transforms that into 700 J of kinetic energy, 100 J of sound, and 200 J of heat, what is his efficiency?

a)

80%

b)

70%

c)

20%

5.

What is the efficiency of the machine if the input is 263 J and the output is 142 J?

a)

6.26%

b)

54%

c)

100%

d)

260%

6.

Total energy = 200J
Useful energy = 20J

Workout the efficiency of this lightbulb.
$efficiency\ =\ \frac{useful\ enegy}{total\ energy\ in}\ \times100$

a)

100%

b)

80%

c)

40%

d)

10%

7.

Total energy = 350J
Useful energy = 70J

Workout the efficiency of this iphoneX.
$efficiency\ =\ \frac{useful\ energy}{total\ energy\ in}\ \times100\%$

a)

100%

b)

80%

c)

40%

d)

20%

8.

Total energy = 34000J
Useful energy = 340J

Workout the efficiency of this vintage VW Beetle.
$efficiency\ =\ \frac{useful\ energy}{total\ energy\ in}\ \times100\%$

a)

100%

b)

10%

c)

40%

d)

20%

9.

What is the formula for calculating energy efficiency?

a)

$\frac{useful\ output}{total\ input} \times 100\%$

b)

$\frac{total\ input}{useful\ output} \times 100\%$

c)

$\frac{useful\ output}{total\ input} \times 50\%$

d)

$\frac{total\ input}{useful\ output} \times 50\%$

10.

A light bulb uses 60 J of electrical energy and emits 15 J of light energy. What is its efficiency?

a)

25%

b)

50%

c)

75%

d)

100%

11.

Which of the following best describes energy efficiency in a real-world context?

a)

The ratio of useful energy output to total energy input.

b)

The total energy input regardless of output.

c)

The amount of energy lost as heat.

d)

The total energy output regardless of input.

12.

In an experiment, a motor uses 500 J of energy to lift a weight, but only 350 J is used for the actual lifting. What is the efficiency of the motor?

a)

70%

b)

80%

c)

90%

d)

60%

13.

A refrigerator uses 2000 J of electrical energy and removes 1500 J of heat from its interior. What is the efficiency of the refrigerator?

a)

75%

b)

50%

c)

25%

d)

100%

14.

If a car engine converts 1000 J of chemical energy from fuel into 300 J of mechanical energy, what is the efficiency of the engine?

a)

30%

b)

70%

c)

50%

d)

100%

15.

Which of the following statements is true about energy efficiency?

a)

It is always less than 100%.

b)

It can be more than 100%.

c)

It is always equal to 100%.

d)

It is not measurable.

Energy Efficiency Calculations

Total questions: 15

Worksheet time: 15mins

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