Energy Flashcards
Fibreglass wool contains lots of trapped air, how does this insulation reduce the amount of heat lost? (4)
Air is a poor conductor of heat hence, conduction reduces as the fibreglass wool is a poor conductor of heat. The trapped air particles can’t move hence, convection is also reduced.
How does the process of convection cause air movement as it’s heated
As air moves into the furnace and coal fire heats up the air hence, the air expands as the particles near the furnace gain kinetic energy and move around faster; the air decreases density and rises. The colder air from outside becomes dense and falls thus repeating the convection current
How does fibreglass wool insulation decrease energy loss by convection (2)
Air particles in the fibres can’t move hence the convection current is reduced
Difference between the orbit of a moon and a planet
Moons orbit planets
Plants orbit stars
Why did the golf ball travel further on the moon compared to the earth
The ball weighs less on the moon allowing it to travel further and there is less air resistance compared to the earth
Why does the car have greater acceleration and uses less fuel when mass is removed
m = F/a
As the mass decreases of the vehicle, the car produces the same amount of force whilst accelerating more as there’s less energy being used
How do radiators heat the room by convection?
- Radiators are placed at the bottom
- Air near the radiator expands as the air particles gain kinetic energy and move around faster hence, the spaces between the air particles expand
- The density of air, then, decreases and the warmer air rises.
- Colder air falls, as it’s denser, causing the convection current to repeat
How can radiators be designed to maximise heat transfer by convection
Large surface area
One assumption made when calculating the energy transferred
Rate of transfer is constant
Discuss why conduction’s the main way that thermal energy is transferred between two solid objects
Both are solid hence, convection’s impossible
Both objects are at different temperatures
Both objects are in physical contact with one another hence, it’s likely to be conduction
What is meant by non-renewable
Cannot be replaced
What are examples of non-renewable sources of energy
Coal, Oil, Gas, and Nuclear energy
How can burning fossil fuels be harmful to the environment
Releases Carbon Dioxide which increases causes Global Warming
Disadvantages of using solar power
Sun doesn’t always shine, some areas of land may not be suitable for solar power, generates too little energy and they are too expensive
Properties of shiny surfaces?
- Poor emitter of radiation
- Poor absorber of radiation
- Therefore, reducing heat loss by radiation
