Energy

Question 1

What is energy?

Answer 1

Energy is responsible for things happening, and it can be stored in a variety of energy stores

Question 2

How can energy be transferred?

Answer 2

Energy can be transferred through -

• heating
• waves
• electric current
• force

Question 3

Can energy be created or destroyed?

Answer 3

No, energy cannot be created or destroyed, although it can be transferred

Question 4

What is energy measured in?

Answer 4

Joules

Question 5

Some energy stores are…

Answer 5

Elastic potential
Chemical potential
Gravitational potential
Nuclear
Internal
Magnetic

Question 6

Some energy transfers are…

Answer 6

Mechanical energy
Light energy
Sound energy
Thermal energy 
Kinetic energy
Electrical energy

Question 7

What is work done?

Answer 7

Work done is when a force causes a body to move, so work is done on the body

Question 8

What is the equation for work done?

Answer 8

Work done = Force x Distance moved in direction of force

Question 9

What is the symbol equation for work done?

Answer 9

WD = FD

Question 10

Note on work done…

Answer 10

One joule is the work done when a force of 1 Newton moves through a distance of 1 metre

Question 11

Work done example…

Answer 11

If you have to exert an UPWARD FORCE of 10N in order to raise a book through a vertical distance of 1.5M, the work dome is 15J - this is also the amount of energy transferred

Question 12

What is the formula for kinetic energy?

Answer 12

KE = 1/2MV^2

Kinetic Energy = 1/2 x Mass x Speed^2

Question 13

What is the formula of Gravitational Potential Energy?

Answer 13

GPE = Mass x Gravitational field strength x (delta) Height

(Delta)GPE = MG(delta)H

Question 14

What is important to consider when comparing fuels?

Answer 14

Energy Density

Question 15

What is Power?

Answer 15

POWER is ENERGY TRANSFERRED per unit of TIME

Question 16

What is the equation (Word and Symbol for Power)?

Answer 16

Power = Energy Transferred / Time

P = E / T

P = WD / T

Question 17

What is the equation for Efficiency?

Answer 17

Efficiency = Useful energy transferred by the device / Total Energy

Question 18

What are some reasons for devices wasting energy?

Answer 18

Devices waste energy through friction, resistance, air resistance and sound.

Question 19

How can someone reduce energy wasted?

Answer 19

Lubricate moving parts, Use wires with little electrical resistance, streamline shapes to counter air resistance, cut out noise by reducing vibration

Question 20

What is a renewable energy resource?

Answer 20

One that is replenished as it is used

Question 21

What are some uses of energy resources?

Answer 21

Transport, electrical energy use in homes, thermal use for heating

Question 22

What is the equation for elastic potential energy?

Answer 22

Ep = 1/2ke^2

Question 23

What is the unit for a spring constant?

Answer 23

N/m

Question 24

Why might motors have a high kinetic energy?

Answer 24

Because it has a high power

Question 25

What is a biofuel?

Answer 25

A renewable, carbon neutral fuel obtained from a living or recently living organism

Question 26

How does a wind turbine work?

Answer 26

- Wind passes over turbine blades - Making the turbines rotate - Which drives a generator - Producing electricity

Question 27

How does a wave generator work?

Answer 27

- Waves rock a floating turbine - Moving turbine up and down - Generating electricity

Question 28

How is geothermal energy harvested?

Answer 28

- Comes from energy released deep from within Earth - Energy heats up surrounding rocks - Deep holes are drilled and water is pumped down - Water comes back to surface as steam - Which is used to drive turbines

Question 29

How do solar cells work?

Answer 29

- Transfers energy through EM radiation from Sun - Straight into electricity - So very useful to power small devices - Such as watches

Question 30

Renewable Energy resources advantages

Answer 30

- Wil never run out | - Do not cause environmental harm

Question 31

Renewable Energy resources disadvantages

Answer 31

- Cannot currently meet world energy demand | - Unreliable

Question 32

What is the specific heat capacity?

Answer 32

The energy required to heat 1kg of a substance by 1°C

Question 33

How can we reduce energy wasted in houses?

Answer 33

- Fibreglass loft insulation reduces rate of energy transfer through the roof - Cavity wall insulation reduces rate of energy transfer through walls - Aluminium foil behind radiators reflects radiation back into the room - Double glazed windows reduces rate of energy transfer through windows - Thick, low conductivity bricks reduces rate of energy transfer through outer walls

Question 34

Advantages of Nuclear Power

Answer 34

- Do not produce greenhouse gases | - Transfer much more energy per kilogram than fossil fuels

Question 35

Disadvantages of Nuclear Power

Answer 35

- Radioactive waste is a biproduct that must be stored fore years - Accidents can happen putting lives at risk

Question 36

Equation for Efficiency?

Answer 36

Useful output energy transfer / Total input energy transfer