Topic 3 - Conservation of Energy

Question 1

SP3a - What are the 9 energy stores?

Answer 1

• Kinetic
• Thermal
• Gravitational Potential
• Elastic Potential
• Sound
• Light
• Chemical
• Nuclear
• Electrical

Question 2

SP3a - By what processes can energy be transferred?

Answer 2

• Heating
• Forces
• Electricity

Question 3

SP3a - What is the law of the conservation of energy?

Answer 3

• Energy cannot be created or destroyed, only transferred between stores.
• In a closed system, the total start energy = the total end energy

Question 4

SP3a - What is unit for measuring energy?

Answer 4

Joules (J)

Question 5

SP3a - What diagram might you use to display the transfer of energy?

Answer 5

A sankey diagram, The width of the bars represent the amount of energy.

Question 6

SP3b - What is it called when energy transfers to its surroundings by heating?

Answer 6

Dissipation

Question 7

SP3b - What might you do to moving parts to reduce enrgy loss and why?

Answer 7

• Use a lubricant.
• Moving parts cause friction which causes enrgy to dissipate losing energy.
• Lubrication reduces friction and thus energy loss by friction.

Question 8

SP3b - What is the most common form of wasted energy?

Answer 8

Thermal

Question 9

SP3b - How do you calculate efficiency?

Answer 9

total useful energy output / Total energy input Efficiency is on a scale of 0 to 1. To calculate it s a percentage, x100

Question 10

SP3b - How do you distiguish useful and wasted energy on a sankey diagram?

Answer 10

The useful energy has an arrow going staright while the wasted energy arrow turns off.

Question 11

SP3c - How is a convection current formed?

Answer 11

Part of a fluid (Liquid/gas) that is warmer than the rest rises up once it reaches the top it looses thermale enrgy and sinks back down. This forms a current.

Question 12

SP3c - Why do cavities in walls help insulate a house?

Answer 12

• When thermal energy wants to travel it requires particles to travel throgh.
• It gives energy to these particles which causes heat.
• A cavity in the wall means that there is air in which particles will collide less and heat will pass through less, so heat can’t escape as easily.

Question 13

SP3c - How is a flask able to maintain the temperature of its contents?

Answer 13

• Silver coating on the outside and inside reflects radiation which would transfer thermal energy
• Glass walls with vacuums between create a cavity stopping heat from entering or escaping
• Plastic stopper stops heat from escaping

Question 14

SP3d - What is the formula for change in gravitational potential energy.

Answer 14

ΔGPE = m x Δh x g

(change in GPE is mass x change in height x gravitational field strength)

Question 15

SP3d - What is the gravitational field strength on earth?

Answer 15

9.81 (Can be rounded to 10) m/s² or N/Kg

Question 16

SP3d - What is the formula for Kinetic energy?

Answer 16

KE = ½ x m x v²

(Kinetic energy = mass x velocity² divided by 2)

Question 17

SP3d - As an object falls describe the change in energy stores in terms of GPE and KE.

Answer 17

• As an object looses height, it looses GPE this ‘lost’ energy transfers, mostly, into kinetic energy as it is moving.
• Some other energy may transfer into sound energy

Question 18

SP3e - What are the four main types of non-renewable energy sources?

Answer 18

• Fossil fuels:
  
  • Natural gas
  • Coal
  • Oil
• Nuclear

Question 19

SP3e - Apart from the lack of sustainability, why is burning fossil fuels not beneficial?

Answer 19

It releases Carbon dioxide and other gases that are harmful for the environment as they contribute to climate change.

Question 20

SP3f - What are the pros and cons of using solar panels and solar energy?

Answer 20

Pros:

• Will never run out
• Won’t release carbon dioxide once installed

Cons:

• Energy output depends on sun and so may not always be available

Question 21

SP3f - What are the pros and cons of using wind turbines?

Answer 21

Pros:

• Will never run out
• Won’t release carbon dioxide once installed

Cons:

• Many have to be installed and they have low output
• Takes up large spaces and soem say this spoils the view
• Not reliable

Question 22

SP3f - What are the pros and cons of hydroelectric energy?

Answer 22

Pros:

• Very reliable
• Will never run out
• Won’t release carbon dioxide once installed

Cons:

• Habitats destroyed
• Only useful when water sources are nearby

Question 23

SP3f - What are the pros and cons of Tidal energy?

Answer 23

Pros:

• Extremely reliable
• Will never run out
• Won’t release carbon dioxide once installed

Cons:

• Some argue that it harms wildlife

Question 24

SP3f - What are the pros and cons of wave energy?

Answer 24

Pros:

• Reliable
• Will never run out
• Won’t release carbon dioxide once installed

Cons:

• Small scale and experimental
• Low output

Question 25

SP3f - What are the pros and cons of geothermal energy?

Answer 25

Pros:

• Will never run out
• Won’t release carbon dioxide once installed
• Extremely reliable

Cons:

• Only useful near volcanic sites

Question 26

SP3f - What are the pros and cons of biofuel?

Answer 26

Pros:

• Will never run out
• Carbon neutral (Burning fuels releases carbon put planting plants took in carbon so its neutral)
• Useful as they can power vehicles

Cons:

• Can take up space that could be used for food, this can increase the price of food.