P1,P2,P3 Flashcards
1 KW = ? KWH
1 KW = 1 KWH
3 advantages of nuclear power
- Doesnt contribute to climate change
- Low fuel costs
- Very large amounts of energy for small quantites of fuel
3 main fossil fuels are
- Coal
- Oil
- Natural gas
3 problems with renewable energy resources
- politics can interfere
- they cost more
- they are less reliable
4 methods of energy transfer
- heat
- waves
- mechanical work
- electrical work
An advantage of using fossil fuels?
Easy to obtain
Describe the energy change when a ball is thrown upwards and then returns to its original position.
- upwards KE is converted to GPE
- peak: maximum GPE, zero KE
- Downwards GPE is converted to KE
Disadvantage of geothermal power
- Location dependent
Disadvantages of hydroelectricity
- visual pollution
- destruction of habits
- disrupts flow of river
Examples of renewable energy resources
- The Sun
- Wind
- Water waves
- Geothermal
- Biofuels
Explain the environmental impacts of burning fossil fuels
- Carbon dioxide released causes global warming
- Sulphur dioxide can lead to acid rain, damaging habitats and crops
Explain why a bungee cord jumper slows down the the cord stretches
KE decreases as it’s converted to elastic potential energy since KE is proportional to (velocity)^2
as KE decreases so does velocity
For the same braking force, explains what happens to the braking distance if the speed doubles.
- doubling speed increases the kinetic energy
- kinetic energy increases by a factor of 4 (2^2)
- work done (by brakes) to stop the car increases
- work done is force × distance and braking force is constant
- so if work done increases by 4 then the braking distance must increase by 4
Give 3 reasons why a toaster is only 65% efficient
- sound energy is wasted
- light energy is wasted
- kinetic energy is wasted
Give one reason why electricity use had decreased in the past decade
Household appliances have become more energy efficient
How can the efficiency of a machine with moving parts be improved?
Lubricate any moving parts to reduce friction and therefore energy loss due to heating
How can the efficiency of a radiator be improved?
Installing metal foil sheets behind the radiator to reflect the heat back into the room
How can the rate of energy transfer from houses be reduced?
- loft insulation
- cavity wall insulation
- double glazed windows
- aluminium foil behind radiator
How can you reduce the energy transfer in any given situation?
- thermal conductivity should be low as possible
- the thickness of the insulating layer should be as thick as possible
How do cavity wall insulation (gaps of air between inside and outside walls) reduce heat transfer?
- air is a poor conductor of heat
- it reduces heat transfer by conduction
How does the mass of an object, affect the time it takes for that object to heat up?
the greater the mass of the object the more slowly it’s temperature increases
How is energy transferred as a ball falls to the ground?
As the ball falls towards the ground, its gravitational potential energy is transformed into kinetic energy.
Law of conservation of energy
The law of conservation of energy states that energy can neither be created nor destroyed - only converted/transferred from one form to another.
Lubricating certain machines or bikes reduces which type of force?
friction
Name 2 main useful energy transfers that take place in the washing machine
- electrical to thermal
- electrical to kinetic
On a rollercoaster, gravitational energy is transferred to which other two energy stores?
Thermal and kinetic
State the units for specific heat capacity
J/C/Kg
Suggest where the highest rate of unwanted energy transfer occurs in the house
Roof
Types of energy stores
- kinetic energy
- internal energy
- elastic potential energy
- gravitational potential energy
- electrical energy
- magnetic energy
What are the two main nuclear fuels?
Uranium and plutonium are the two most common nuclear fuels.