Energy transfers Flashcards
1
Q
Different types of energy stores:
A
- Chemical energy e.g. fuel, food, batteries
- Kinetic energy e.g. man running
- Gravitational e.g. sitting on a ski lift
- Elastic e.g. elastic bands
- Nuclear energy e.g. uranium fuel
- Thermal energy e.g. hot water
- Magnetic energy
- Electrostatic
2
Q
How may energy be transferred?
A
- Mechanically
- Electrically
- By heating
- By radiation (light and sound)
3
Q
Define conservation of energy
A
Energy cannot be created or destroyed, it can only be converted from one form into
another
4
Q
Describe the energy changes in an object falling to ground
A
- Kinetic energy increases
- Gravitational potential energy decreases
5
Q
Describe the energy changes when a falling object hits the ground
A
- Kinetic energy decreases
- Wasted energy is thermal and sound energy
6
Q
How may thermal energy transfer take place?
A
- By conduction, convection and radiation
7
Q
Describe the process of conduction
A
- Heat makes the particles vibrate more
- Particles collide with each other and pass their kinetic energy along
- Eventually the energy will be spread through the solid
8
Q
Describe the process of convection
A
- Heat causes particles to gain kinetic energy
- Particles vibrate and spread out
- Particles become less dense
- Particles rise
- Particles cool and sink setting up a convection current
- Process repeats
9
Q
Radiation summary:
A
- White, shiny surfaces reflect radiation
- Dark, matt surfaces absorb radiation
- The hotter the substance, the more radiation that occurs
10
Q
How does heat transfer occur in a vacuum?
A
- By radiation only
11
Q
How does a vacuum flask prevent heat loss?
A
- Shiny walls reflect infra-red radiation
- Plastic lid is a good insulator
- Vacuum prevents heat loss by conduction and convection
12
Q
How may the rate of energy transfer be reduced at home?
A
- Loft insulation - fibreglass is a good insulator
- Cavity wall insulation - foam is a good insulator and prevents convection currents being
set up - Aluminium foil behind radiators - reflects IR
- Double glazed windows - vacuum between glass slows conduction and stops IR
13
Q
A
