energy (paper 1)

Question 1

what is convection

Answer 1

where energetic particles move from hotter to cooler regions

Question 2

what is thermal conductivity

Answer 2

a measure of how quickly energy is transferred through a material through conduction

Question 3

what is conduction

Answer 3

the process where vibrating particles transfer energy to neighbouring particles

Question 4

equation for elastic potential energy

Answer 4

2
1/2 x k x e

Question 5

nuclear power

Answer 5

nuclear fuel (uranium or plutonium) uses the energy released from unstable atoms (isotopes) when they split, this process is called nuclear fission

nuclear fission releases energy in the form of heat, which boils water to steam and then the steam turns a turbine

Question 6

how are biofuels carbon neutral

Answer 6

they take in the same amount of carbon they release when they are burnt

Question 7

how do power stations work

Answer 7

boiler - coal is burnt and heat is used to turn water into steam

turbine - steam is used to turn the turbine , kinetic energy of the steam is passed onto the kinetic energy of the turbine

generator - turbine is connected to the generator, so the generator spins , kinetic energy is converted to electrical energy

Question 8

what does a black body do

Answer 8

a body that absorbs infrared radiation at the same rate as it emits it will remain at a constant temperature. it is said to be in thermal equilibrium

Question 9

what is a black body emitter

Answer 9

an object that absorbs all radiation that hits it and does not reflect any

Question 10

what is the best emitter of infrared radiation

Answer 10

matte black and is also the best absorber

Question 11

pay back time equation

Answer 11

cost to install
———————
saving each year

Question 12

what do the best insulators have

Answer 12

the lowest thermal conductivity value and the more effective a material is as an insulator the less heat energy it will transfer

Question 13

equation for specific heat capacity

Answer 13

energy transferred
—————————
mass x temp change

Question 14

what is the unit for specific heat capacity

Answer 14

J/kg degree celsius

Question 15

what is the specific heat capacity of a substance

Answer 15

the energy needed to raise the temperature of 1kg of the substance by 1 degree celsius

Question 16

the rate of energy transfer across a material depend on;

Answer 16

the temperature difference across the material

the thickness of the material

the thermal conductivity of the material

Question 17

thermal insulation

Answer 17

is to reduce the rate of heat energy transfer

Question 18

what does it mean by insulate

Answer 18

to block from electricity or heat
means to reduce the amount of energy transfer across a material

Question 19

thermal conductivity key points

Answer 19

energy transfer by conduction depends upon thermal conductivity

thermal conductivity of a material refers to the rate at which it transfers heat energy

the higher the thermal conductivity value of a metal the more energy it transfers through it per second

Question 20

what are insulators

Answer 20

materials that do not contain free electrons so they are poor conductors

Question 21

what are the 3 methods of heat transfer

Answer 21

conduction , convection and radiation

Question 22

what does a bigger spring constant mean

Answer 22

means it’s harder for the spring to be compressed and stretched

Question 23

equation for elastic potential energy

Answer 23

2
1/2 x k x e

Question 24

equation for power

Answer 24

energy
———-
time

Question 25

equation for efficiency

Answer 25

useful energy
———————. x100
total energy

Question 26

equation for work done

Answer 26

force x distance

Question 27

equation for kinetic energy

Answer 27

1/2 x mass x velocity squared

Question 28

equation for gravitational potential energy

Answer 28

m x g x h

Question 29

investigating specific heat capacity practical method

Answer 29

1. to investigate a solid material - copper , you will need a block of the material with wo holes in it for the heater and the thermometer
2. measure the mass of the block then wrap it in an insulating layer such as a thick layer of newspaper to reduce the energy transferred from the block to the surroundings, insert a thermometer and heater
3. measure the initial temperature of the block and set the potential difference of the power supply to 10V , turn on the power supply and start a stopwatch
4. as the block heats up, use the thermometer to measure its temperature every minute , keep an eye on the ammeter, it should not change
5. when you have collected at least 10 readings turn off the power supply
6. you can then use the specific heat capacity equation to find the specific heat capacity of the material

Question 30

what is the conservation of energy

Answer 30

energy can be transferred usefully, stored or dissipated , it can never be created or destroyed

Question 31

how do radiators create convection currents

Answer 31

energy is transferred from the radiator to the nearby air particles by conduction

the air by the radiator becomes warmer and less dense

this warm air rises and is replaced by cooler air , the cooler air is then heated by the radiator

at the same time, the previously heated air transfers energy to the surroundings , it cools, becomes denser and sinks

this cycle repeats, causing a flow of air to circulate around the room - this is a convection current

Question 32

what are things you an do to prevent energy loss through heating

Answer 32

thick walls

use insulation;
- cavity wall insulation
- loft insulation
- double glazed windows
- draught excluders

Question 33

practical for investigating the effectiveness of different insulators method

Answer 33

1. boil water in a kettle , pour some of the water into a sealable container to a safe level, measure the mass of the water in the container
2. use a thermometer to measure the initial temperature of the water
3. seal the container and leave it for five minutes , measure this time using a stopwatch
4. remove the lid and measure the final temperature of the water
5. pour away the water and allow the container to cool to room temperature
6. repeat this experiment but using a different material to wrap the container in , make sure you use the same mass of water each time
7. you can them find the temperature difference with each material and which one is the best insulator