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.
What can efficiency never be greater than?
100%
What century did the UK see an increased demand in electricity usage?
20th
What does the amount of kinetic energy an object has depend upon?
- the mass of the object
- the speed of the object
What does the energy transfer per second of a material depend on?
- temperature across material
- thickness of material
- thermal conductivity of material
What energy transfer happens in many musical instruments?
Kinetic to sound
What happens to the amount of infrared radiation that is emitted from an object, if the temperature increases?
- higher the temperature of an object, the more infraed radiation more given time
What happens to the GPE of an object when it moves up/down?
GPE increases when up and decreases when down
What is a biofuel?
A biofuel is any fuel taken from living or recently living organisms.
What is a closed system?
A closed system is a system in which no energy transfers take place and no energy can enter or leave, meaning the net change in the total energy is zero.
What is a renewable energy resource?
A renewable energy resource is one that is replenished as it is used
What is a system?
An object or group of objects
What is an electrical insulator?
A material that doesn’t allow electric currents to pass through it
What is chemical energy?
Chemical energy is energy stored in the bonds of atoms and molecules. This energy can be transferred during chemical reactions and can be found in foods, fuels or batteries.
What is conduction?
Conduction is the process where vibrating particles transfer energy to neighbouring particles.
What is convection?
The transfer of heat from one place to another due to the movement of a fluid
What is dissispation?
The process of energy being transferred, or lost, to the surroundings.
What is elastic potential energy?
Elastic potential energy refers to the energy stored in a spring object when it is stretched or squashed.
What is gravitational potential energy?
Gravitational potential energy is energy an object possesses because of its position in a gravitational field. e.g An object above the ground
What is Hooke’s law?
The extension of a spring is directly proportional to the force applied, provided that the limit of proportionality is not exceeded.
What is input and output energy?
Input refers to the amount of energy put into a device, and output refers to the amount of energy that comes out.
What is kinetic energy?
Kinetic energy of an object is the energy that it possesses due to its motion.
What is power the rate of?
Energy transfer or work done
What is specific heat capacity?
The specific heat capacity of a substance is the amount of energy needed to raise the temperature of 1kg of the substance by 1 degrees Celsius.
What is the main energy transfer for a long-distance runner?
Chemical energy —-> Kinetic energy
What is the main energy transfer in a rollercoaster?
Gravitational potential to kinetic
What is the main type of energy transfer in a catapult?
Elastic potential to kinetic
What is the main useful energy transfer that happens in cars?
The main useful type of energy transfer that happens in cars is chemical (in the fuel) to kinetic to turn the wheels.
What is the unit of latent heat of vaporisation?
J/kg
What is thermal energy?
Thermal energy stores refer to the energy a substance has due to its temperature.
e.g Heat
What is useful energy?
Useful energy is energy transferred to where it is wanted in the way that it is wanted.
What is wasted energy?
Wasted energy is energy that is not usefully transferred. e.g Heat caused by friction
What is work done always equal to?
Energy transferred
What kind of energy stores are the waves and tides of the sea?
Kinetic
What methods of heat transfer can occur in a vacuum?
Radiation
What property of an object is a measure of the energy in the kinetic stores of its particles?
Temperature
What proportion of energy in the UK comes from fossil fuels?
3/4
What type of energy do batteries store and what do they convert it to?
A battery is a device that stores chemical energy and converts it to electrical energy
What type of energy is stored within fossil fuels?
Chemical
Where does the energy come from in geothermal power stations?
The energy that is used in geothermal power stations comes from the Earth’s hot core.
Which renewable energy source relies on their being volcanic activity close to the surface?
Geothermal energy
Which type of appliance would convert electrical energy into sound energy?
A speaker
Which type of fossil fuel power station has the shortest start-up time?
Gas
Why does the energy demand in the UK spike during 6pm and 9pm?
During those times most families are at home using lights, electrical devices and heating
Why is wood considered a renewable resource, while coal is considered non-renewable?
Wood can be replenished (grown in the form of trees).
