Topic 3 - energy (term 1)

Question 1

What is the law of conservation of energy?

Answer 1

Energy cannot be created or destroyed - it can only be transferred.

Question 1

How do you increase efficiency?

Answer 1

You reduce waste energy lost.

Question 2

What is the gravity on earth?

Answer 2

10N/kg

Question 3

Does thickness or length tell you how much energy is transferred on a Stanley diagram?

Answer 3

Thickness

Question 4

How do you figure out the change in gravitational potential energy?

Answer 4

🔼 GPE = m * g * 🔼h

Question 5

How do you figure out the amounts of energy associated with a moving object?

Answer 5

KE = 1/2 * m * V^2

Question 6

How do you figure out efficiency?

Answer 6

Efficiency = useful energy transferred/total energy supplied (*100)

Question 7

What happens to wasted energy?

Answer 7

It dissipates into its surroundings

Question 8

What is energy measured in?

Answer 8

Joules (j)

Question 9

What are the different ways to insulate houses?

Answer 9

• double glazing on windows
• insulation in walls
• carpet
• doors have gaps at bottom
• fibreglass
• fill gaps between the floor and skirting board.

Question 10

How is energy wasted in kettles?

Answer 10

Hearing via particles means the thermal store of the surroundings and kettle are filled.

Question 11

How can wasted energy through kettles be stopped?

Answer 11

Thermal insulation, e.g. kettles made of plastic on the outside.

Question 12

How is energy wasted in machines?

Answer 12

Friction between moving components means the thermal store of the surroundings and the object is filled.

Question 13

How can wasted energy through machines be stopped?

Answer 13

Use oil to reduce friction and so replace heat loss.

Question 14

What is thermal conductivity?

Answer 14

A measure of how good a material is at letting heat pass through it.

Question 15

What is a conductor?

Answer 15

High thermal conductivity (e.g. metal)

Question 16

What is an insulator?

Answer 16

Low thermal conductivity (e.g. plastic)

Question 17

Give a flow diagram of a kettle.

Answer 17

electrical -> kettle -> thermal
-> wasted thermal

Question 18

Describe how heat loss through walls can be reduced.

Answer 18

Heat loss through walls can be reduced using cavity wall insulation. This involves blowing insulating material into the gaps between the brick and inside wall. Insulating materials are bad conductors and so this reduces the heat loss by conduction. The material also prevents air circulating inside the cavity, therefore reducing heat loss by convection.

Question 19

What reduces the rate of heat transfer from the ceiling into the roof space?

Answer 19

A thick layer of material with a low thermal conductivity reduces the rate of heat transfer from the ceiling into the roof space.

Question 20

How do you reduce the amount of thermal energy transfer?

Answer 20

We can put an air gap / foam in between the layers.

Question 21

Name all energy sources:

Answer 21

• solar
• hydroelectric
• wind
• nuclear
• tidal
• geothermal
• biomass
• fossil fuel

Question 22

Describe solar energy in more detail.

Answer 22

Cells convert sunlight directly into electrical energy.

Question 23

Describe hydroelectric energy in more detail.

Answer 23

Relies on water falling down from a dam, down a steep incline to turn the turbine.

Question 24

Describe wind energy in more detail.

Answer 24

It relies on wind to turn the turbine which then turns the generator.

Question 25

Describe nuclear energy in more detail.

Answer 25

It relies on radioactive fuels decaying to produce heat to boil the water to make steam.

Question 26

Describe tidal energy in more detail.

Answer 26

The tide going in and out, turning the turbines.

Question 27

Describe geothermal energy in more detail.

Answer 27

Relies on hot rocks in the earth to heat the water which produces steam that turns the turbine.

Question 28

Describe biomass energy in more detail.

Answer 28

Relies on burning living things (like trees) to release heat.

Question 29

Describe using fossil fuels as an energy source in more detail.

Answer 29

Burns coal, oil or gas to produce heat, which boils water to create steam.