P1.2 Using Energy

Question 1

What are the nine types of energy?

Answer 1

Kinetic
Thermal
Chemical
Nuclear
Gravitational potential
Elastic potential
Sound
Electrical
Light

Question 2

What is the energy transfer diagram of pinging an elastic band?

Answer 2

Elastic potential -> kinetic + sound + thermal + gravitational potential

Question 3

What’s the energy transfer diagram of an explosion?

Answer 3

Nuclear -> light + thermal + sound + chemical

Question 4

Why is thermal energy produced a lot in energy transfer diagrams?

Answer 4

Because of friction

Question 5

What are the energy transfer diagrams for someone bungee jumping?

Answer 5

As the person falls:
Gravitational potential -> kinetic
As jumper get pinged back:
Gravitational potential + kinetic -> elastic
When person rises to the top:
Elastic -> GP + kinetic
Then
Gravitational potential -> thermal

Question 6

What’s useful energy?

Answer 6

Energy transferred to where it’s wanted

Question 7

What’s wasted energy?

Answer 7

Energy that isn’t usefully transferred

Question 8

What happens to wasted energy?

Answer 8

It spreads out to the surroundings

Question 9

In an electric heater what’s the useful energy and the wasted energy?

Answer 9

Useful : thermal

Wasted: sound

Question 10

In a TV what’s the useful energy and the wasted energy?

Answer 10

Useful: sound + light
Wasted: thermal

Question 11

What’s the energy transfer diagram for a pendulum?

Answer 11

GP -> kinetic -> GP

Question 12

What’s the conservation of energy?

Answer 12

Energy can’t be created or destroyed, only transferred

Question 13

What’s efficiency?

Answer 13

A measure of how good a device is at changing energy from one to another.

Question 14

The more efficient the device is, the ______ energy is wasted.

Answer 14

Less

Question 15

How do you calculate efficiency?

Answer 15

Useful energy out / total energy in

Question 16

What’s the unit for efficiency? How can you tell if your right?

Answer 16

Doesn’t have units

It’s a number between 0 and 1 or a percentage.

Question 17

In a radio:
300J = electrical energy
96J = sound energy
A)How much energy is wasted?
B)What energy is wasted?
C)What's the efficiency?

Answer 17

A) 300-96 = 204J

B) heat energy

C) 96/300 = 0.32 or 32%

Question 18

What key things do you have to remember for a sankey diagram?

Answer 18

Input energy is on the left
Useful energy goes out to the right
Wasted energy goes down
Everything has to be to scale eg. 10J = 1 square

Question 19

What’s the approximate efficiency of a filament bulb?

Answer 19

5%