P5. Energy and Power

Question 1

What is energy?

Answer 1

A number in joules that tells you what is possible but doesnt tell you what will happen

Question 2

What is an energy store?

Answer 2

A store indicates amount of energy in joules

Question 3

What are the different types of stores? 6

Answer 3

Chemical
Thermal
Kinetic
Gravitational
Nuclear
Elastic

Question 4

What is an example of a chemical store?

Answer 4

Coal and oxygen, glucose and oxygen

Question 5

What is an example of a thermal store?

Answer 5

Hot bath

Question 6

What is an example of a kenetic store?

Answer 6

Moving car

Question 7

What is an example of a gravitational store?

Answer 7

Skier at top of hill

Question 8

What is an example of a nuclear store?

Answer 8

Hydrogen in sun

Question 9

What is an example of an elastic potential energy store?

Answer 9

Stretched elastic band

Question 10

What is an example of a magnetic store?

Answer 10

Opposite poles of magnet held apart

Question 11

What are the 4 ways energy is transferred?

Answer 11

Mechanical
Heated by radiation
Electrical
Heated by particles

Question 12

What is the conservation of energy?

Answer 12

Energy cannot be created nor destroyed, energy can only be transferred between stores

Question 13

How do you do an energy analysis?

Answer 13

Choose two points in a process
Identify which stores have more or less energy in them at those points
Work out which type of transfer has transferred the energy between stores

Question 14

How do you know which energy transfer it is?

Answer 14

Mechanical is most things
Electrically - electrical current
Rest are self explanatory

Question 15

When is energy transferred in an electric current?

Answer 15

When a charge is moved.

Question 16

In electrical devices, energy is transferred when a charge moves from…? (2)

Answer 16

From chemical potential energy store in battery.
From chemical or nuclear store in a power station

Question 17

What do electrical appliances transfer electrical energy from?

Answer 17

Chemical potential store

Question 18

What affects the cost of electricity? 2

Answer 18

Power
Time

Question 19

What is power?

Answer 19

Power is energy transferred every second?

Question 20

What is the unit of power?

Answer 20

Watts

Question 21

What is energy dissipation?

Answer 21

You cannot use the energy in the surroundings, it has been dissipated and is no longer in a store that is useful

Question 22

What is lubrication?

Answer 22

You can reduce energy dissipated due to friction by lubrication

Question 23

What does insulation do?

Answer 23

You can reduce the energy dissipated due to heating by insulation

Question 24

What is an insulator?

Answer 24

Material that doesnt conduct very well between hot and cold object

Question 25

True or False: Using lubrication or insulation reduces energy transferred to thermal store of surroundings?

Answer 25

True

Question 26

What does the rate at which energy is transferred through walls depend on? 3

Answer 26

Thickness of the wall What they are made of Difference in temperature between two sides of the wall

Question 27

What is efficiency?

Answer 27

How good a device is at converting energy into useful forms of energy known as its efficiency

Question 28

What do you need to think about when building walls? Efficiency

Answer 28

Thermal conductivity of the material

Question 29

What is thermal conductivity?

Answer 29

a measure of how quickly energy transfers through a material by conduction.

Question 30

What is better for staying warm? Low or high thermal conductivity?

Answer 30

Low

Question 31

Why can igloos stay warm?

Answer 31

Ice has a low thermal conductivity

Question 32

if you want to increase efficiency, what do you need to reduce? ( not examples)

Answer 32

You need to reduce wasted energy

Question 33

How do you reduce the wasted energy?

Answer 33

Use Insulation to reduce heating of surroundings Use technology that are better at their job