YEAR 9 – Topic 1 – Energy, Work And Power

Question 1

4.02 describe energy transfers involving energy stores.

Answer 1

.

Question 2

4.02 List 8 energy stores.

Answer 2

– Kinetic Energy
– Chemical Energy
– Gravitational Potential Energy
– Elastic Potential Energy
– Thermal Energy
– Magnetic Energy
– Electrostatic Energy
– Nuclear Energy

Question 3

4.02 Name the 4 ways in which energy can be transferred:

Answer 3

– Mechanically (forces)
– Electrically (wires and circuits)
– By Heat (conduction, convection, radiation)
– By Radiation (light and sound)

Question 4

4.02 Describe the energy transfers in a radio.
Include input energy, useful output energy and ‘wasted’ energy.
Also include how it is transferred.

Answer 4

Input energy = electrostatic potential (which has been electrically transferred from KE at a power station)
Useful output energy = sound
‘Wasted’ energy = heat

It is transferred electrically.

Question 5

4.02 Describe the energy transfers in a car rolling down a slope.
Include input energy, useful output energy and ‘wasted’ energy.
Also include how it is transferred.

Answer 5

Input energy = GPE
Useful output energy = KE
‘Wasted’ energy = heat + sound

It is transferred mechanically.

Question 6

4.02 Describe the energy transfers in a bunsen burner.

Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 6

Input energy = chemical energy
Useful output energy = heat
‘Wasted’ energy = light

It is transferred by heating.???

Question 7

4.02 Describe the energy transfers in a solar helicopter.

Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 7

Input energy = light (nuclear from the sun)
Useful output energy = KE
‘Wasted’ energy = Heat

It is transferred radiation.

Question 8

4.02 Describe the energy transfers in a wind up toy.

Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 8

Input energy = elastic potential energy
Useful output energy = kinetic + sound
‘Wasted’ energy = Heat

It is transferred mechanically.

Question 9

4.02 Describe the energy transfers in a battery powered toy.

Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 9

Input energy = chemical
Useful output energy = sound + KE
‘Wasted’ energy = heat

It is transferred electrically (in the wires).

Question 10

4.02 Describe the energy transfers in a light bulb.

Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 10

Input energy = electrostatic potential (which has been electrically transferred from KE at a power station)
Useful output energy = light
‘Wasted’ energy = heat

It is transferred electrically.

Question 11

4.02 Describe the energy transfers in a whirling siren around my head.
Include input energy, useful output energy and ‘wasted’ energy.
Also include how it is transferred.

Answer 11

Input energy = KE
Useful output energy = sound
‘Wasted’ energy = heat

It is transferred mechanically.

Question 12

4.03 What is conservation of energy?

Answer 12

Energy cannot be made or destroyed, it is just transferred from one type to another.

Question 13

4.04 How do you workout out efficiency?

Answer 13

. (useful energy output)
Efficiency (%)= —————————— X100
(total energy input)

Question 14

4.02 Describe the energy transfers in a motor raising a mass.
Include input energy, useful output energy and ‘wasted’ energy. Also include how it is transferred.

Answer 14

Input energy = electrostatic potential (which has been electrically transferred from KE at a power station)
Useful output energy = KE
‘Wasted’ energy = Sound + heat

It is transferred electrically.

Question 15

4.05 Be able to describe a variety of everyday and scientific devices and situations, explaining the transfer of input energy, efficiency and be able to use the sankey diagram.

Answer 15

Just know how to do it. It’s not that hard!!!

Question 16

4.06 How does thermal energy transfer by conduction?

Answer 16

Conduction happens in solids. The particles start to vibrate and pass the vibrations onto the next particle and so on. In metals, the atoms have free electrons and this is why they are very good at condition. These free electrons pass the vibrations on more quickly.

Question 17

4.06 How does thermal energy transfer by convection?

Answer 17

A heat source heats fluid particles up, they become less dense, space out and rise. The further ways from the heat source they cool dow, become less dense, come closer together and sink. The cool air comes and takes the place near to the heat source, replacing the particles. This is a convection current.

Question 19

4.06 How does thermal energy transfer by radiation?

Answer 19

Radiation doesn’t need particles to travel through. It travels in electromagnetic waves. Heated things emit these. Idk what else to write!!!

Question 21

4.09 investigate conduction convection and radiation and put into real life context

Answer 21

Make sure you know how how a thermally insulated bottle works. Etc.

Question 22

4.11 What is the relationship between the work done, force and distance moved?

Answer 22

..         /\
          /E \
        /\_\_\_\_\
      /  f  | d \
     ————

Question 23

4.12 What is the relationship between work done and energy transferred? What do they mean?

Answer 23

Work done is equal to energy transferred.
Work done means work doe against a force e.g. lifting a weight.
Energy transferred means…

Question 24

4.16 What is power?

Explain in physics terms

Answer 24

Power is the transfer rate of energy

Question 25

4.17 use the relationship between power, work done and time taken using this equation

Answer 25

. Work done
Power = ——————
Time taken

Question 26

4.07 Explain the role of convection in everyday phenomena

Answer 26

How does a kettle work etc

Question 26

4.08 How are emission and absorption of radiation are related to the colour and texture of the surface?
Use key words:
Black, light, silver, rough, shiny, emitters, absorbers and reflectors in your answer.

Answer 26

Black rough – best emitters, best absorbers, worst reflectors.
Black shiny – good emitters, good absorbers, bad reflectors.
Light rough – bad emitters, bad absorbers, good reflectors.
Light shiny – bad emitters, bad absorbers, good reflectors.
Silver rough – v. bad emitters, v. bad absorbers, v. good reflectors.
Silver shiny – worst emitters, worst absorbers, best reflectors.

Question 26

4.10 How does insulation help prevent unwanted energy transfers (‘heat escaping’)?
Mention conduction convection and radiation in your answer.

Answer 26

The foamy stuff is lined with silver to reflect IR radiation.
The foamy stuff has air holes in it to prevent (most of the) conduction happening.
The foamy stuff has limited space in the air holes so many small ones to stop a convection current from forming.