Energy Transfers

Question 1

Understanding Units
What does the following units measure?
Kilogram (kg)
Joule (J)
Metre (m)
Metre/second (m/s)
Watt (W)
metre/second^2 (m/s^2)
Newton (N)
Seconds (s)

Answer 1

Measure:
Mass
Energy
Length
Speed
Power
Acceleration
Force
Time

Question 2

Energy stores

What is chemical energy?

Answer 2

Stored in food, fuel and batteries

Question 3

What is kinetic energy?

Answer 3

Moving objects

Question 4

Thermal energy

Answer 4

Hot objects

Question 5

Nuclear energy

Answer 5

The potential energy stored in the nucleus of an atom

Question 6

Gravitational Potential Energy

Answer 6

In high positions

Question 7

Elastic potential energy

Answer 7

Stretched, twisted or squashed materials

Question 8

Magnetic energy

Answer 8

From force felt in a magnetic field - stored in magnets

Question 9

Electrostatic energy

Answer 9

Stored between opposite/same charges

Question 10

Energy transfers

Mechanical

Answer 10

When a force acts and something moves

Question 11

Energy transfers

Electrical

Answer 11

When a current flows

Question 12

Energy transfers

By heating

Answer 12

Because of temperature difference

Question 13

Energy transfers

By radiation

Answer 13

A wave such as light, microwaves or sound

Question 14

What does the conservation of energy law state?

What is it in simpler terms: includes equal sign

Answer 14

It states that: Energy cannot be created or destroyed but can be transferred from one store to another
In simpler terms, Total energy in = Total energy out

Question 15

The equation for calculating efficiency

For percentage too

Answer 15

Efficiency = Useful output energy/ Total output energy

If it asks for the percentage, you times the number by 100

Question 16

Triangle for working out the efficiency

Answer 16

Useful output energy at the top, efficiency in the left and total input energy in the right

Question 17

What are sankey diagrams and what do they show?

Answer 17

They represent efficiency and energy transfers. They show the total energy, useful energy and wasted energy

Question 18

What is the key thing to remember when drawing sankey diagrams?

Answer 18

Its the width of the arrow that matters not the length.

Question 19

Step by step introduction to drawing sankey diagrams

Example: A light bulb uses 100J of electrical energy. It radiates 30J of light energy and wastes 70J as heat. Draw the Sankey Diagram.

Answer 19

1. Find a common factor between all of the numbers. In this case, all the numbers are factors of 10. So we can say that our scale is 1 square = 10J
2. Identigy how wide each arrow will be using our scale:
   The total - 100/10 = 10 squares
   Useful - 30/10 = 3 squares
   Wasted - 70/10 = 7 squares
3. And therefore with these number and your scale, you can draw the diagram