Energy

Question 1

Different energy stores

Answer 1

Thermal, kinetic, gravitational potential, elastic potential,chemical,magnetic,electrostatic and nuclear energy

Question 2

How can energy be transferred

Answer 2

Mechanically,electrically,heating or radiation

Question 3

What is a system

Answer 3

A Single or group of objects that transfer energy into or away a system

Question 4

What is a close system

Answer 4

System where neither matter nor energy can enter or leave. The net change in the total energy of a closed system is always zero

Question 5

How is energy transferred by heating provide an an example

Answer 5

The water and kettle heating element can be a two object system. Energy transferred electrically to the thermal energy store of the kettle element , which transfers energy by heating to the water thermal energy store

Question 6

What is work done

Answer 6

Energy transferred against a circuit or by a force moving an object

Question 7

Exmaples of work done

Answer 7

Ball dropped from a height is accelerated by gravity. The grav force does work. It causes energy to be transferred from the balls GPE store to its kinetic energy

Friction between a cars brakes and its wheels does work as it slows down. It causes an energy transfer from the wheel kinetic energy store to the thermal energy store of the surroundings

Question 8

Calculation for kinetic energy

Answer 8

Ek= 1/2MV^2

Question 9

Calcukation for gravitational potential energy

Answer 9

Ep= mgh

Question 10

What happens to the energy store of a raised and falling object

Answer 10

Lifting an object requires gravitational field strength. Energy transferred to gpe energy of the raised object.

When something falls, energy from the its gpe store is transferred to its kinetic energy store. Air resistance acts against the falling object causing energy to be transferred to other energy stores.

Question 11

Calculation for elastic potential energy

Answer 11

Ee= 1/2Ke^2

Question 12

What can stretching an object transfer energy to

Answer 12

Elastic potential energy

Question 13

What is specific heat capacity

Answer 13

Amount of energy needed to raise the temperature of 1kg of a substance 1°c

Question 14

Calculation change in thermal energy

Answer 14

∆E= mc∆0

Question 15

Required practical: specific heat capacity

Answer 15

1) Block of material is needed with two holes for a heater and a thermometer

2) Measure the mass of the block then wrap it in an insulating layer to reduce energy transfer from the block to the surroundings.Then place it ontop of a heat proof mat.

3) Measure the initial temp of the block and set the pot difference of the power supply to 10V and start the stopwatch

4) Turn the power on, energy transferred from the power pack to the heater thermal energy store. Energy is then transferred to the materials thermal energy store by heating , causing the material temp to increase

5) As the block heats up take readings of the temp and current every min for 10 min. Current doesn’t change through thr circuit as temp increases

6) Once collected enough data. Turn off thr power supply. Calculate power supplied to the heated P=VI and then calculate energy transferred E=Pt

Question 16

What is the Conservation of energy principle

Answer 16

Energy can be trabsferred usefully, stored or dissipated but can never be created or destroyed

Question 17

Explain an energy transfer in a phone and a closed system

Answer 17

Phone is used, energy is usefully transferred from the chemical energy store of the battery in the phone. But some energ is dissipated in this transfer to the thermal energy store of the phone.

Cold spoon is dropped into an insulated flask of hot soup and it is then shut. Soup and spoon form a closed system. Energy transferred from the thermal energy of the soup to the useful therm energy store of the spoon. No energy has transferred out net charge =0

Question 18

How to calculate power

Answer 18

E. W
P= —— P=—-
T t

Question 19

Methods to reduce unwanted energy transfers

Answer 19

Frictionsl force causes energy to be dissipated. Lubricants can be usedto reduce the friction between the object surfaces when they move reducing the energy wasted e.g oil.

Thick walls made with a low thermal conductivity will slow rate of energy transfer (buildings cools slowly).

Cavity walls with an outer and inner wall with a gap in the middle. This air gap reduces the amount of energy transferred by conduction through the walls.

Loft insulation reduces convection currents beinf created in lofts

Double glazed windows prevent energy transfer by conduction through the windows

Draught excluders around foors and windows reduce energy transfers by convectiin

Question 20

What is conduction and convection

Answer 20

Conduction: an object is a
Heated, energy transferred to the kinetic energy store of the particles. The particles vibrate and move more ans more energy is being transferred to its kinetic energy store.

Convection: Particles free to move as the particles move faster the space between individual particles increase. The density between the space being heated decreases because liquids and gases can flow, the warmer and less dense region will rise above the denser, cooler regions. Energetic particles mive from hotter to cooler region.

Question 21

How to calcuate efficiency

Answer 21

Useful output energy transfer. Useful power output
Efficiency=————————————————– Efficiency=——————————–
Total input energy transfer. Total power input

Question 22

What are non-renewable resources provide examples

Answer 22

Natural resources from the Earth that provide energy that is finite and will eventually run out

Coal,oil,gas

Question 23

What are renewable resources provide examples

Answer 23

Natural resources from the Earth that will never run out as it can be renewed however these energy sources can be unreliable and provide less energy

Sun,wind,waves,hydro-electric,bio-fuel,tides,geothermal

Question 24

Non-renewable and renewable uses of fuel during modern day life

Answer 24

Transport- non renewable: petrol and diesel powered vehicles use fuel created from oil, coal is used in some old fashioned steam trains to produce steam

Renewable: vehciles that run on pure bio-fuel or a mix of bio-fuel and petrol or diesel

Heating-non reneable: natural gas widely used fuel. The gas is used to heat water, which is then pumped into radiators throughout the home, coal is used to be burnt in fireplaces,electric heaters use electricity generated from non-renewable energy resources

Renewable: geothermal heat pump uses geothermal energy resources to heat buildings,solar waterheaters work by using the sun to heat water which is pumped into the radiators,burning bio-fuels or using electricity generated from renewable resources used for heating

Question 25

Advantages and disadvantages and how are wind turbine used

Answer 25

Advantages: no pollution,renwable resource, no fuel cost wnd minimal running costs

Disadvantages: noisy,spoils the view, unreliable,initiwl costs high, permanent damage to landscape

Wind rotates the turbine which turns the kinetic energy of turbine moving to turn the generator producing electricity

Question 26

Advantages and disadvantages and how are solar panels used

Answer 26

Advantages:no pollution, renewable, reliable, chesp running cost

Disadvanatges: visual pollution, only good during the day, can’t increase he power output, initial costs high

Solar cells absorb the solar waves emitted by the sun. The solar cells use the heat from the sun to boil water creating steam which rotates a turbine turning a generator

Question 27

Advantages and disadvantages and how are geothermal used

Answer 27

Advantages: reliable,little damage to the environment,renewable

Disadvanatges: aren’t many suitable locations,cost of the plant is high compared to energy produced

Radioactive decay of substances underground release heat energy which warms up rocks. A pump drives water to the rocks which turns into steam driving a generator of a turbine producing electricity

Question 28

Advantages and disadvantages and how is hydro-electric power used

Answer 28

Advantages:no pollution,renwable,immediste response to increase demand for electricity,no fuel costs and minimal running costs

Disadvanatges: initial costs high,loss of habitat,unsightly,floods valleys

Holds lots of water in a reservoir until electricity is required. The dam releases water which converts the gpe of the falling water into kinetic energy of turbine driving a generator providing electricity.

Question 29

Advantages and disadvantages and how is wave power used

Answer 29

Advantages:no pollution, renewable,nu fuel costs and minimal running costs

Disadvanatges: fairly unreliable,initial costs high,spoils the view,disturbs the habitat

Waves created by the wind. The waves drives a turbine which transfers kinetic energy into electrical energy in a generator producing electricity

Question 30

Advantages and disadvantages and how are tidal barrages used

Answer 30

Advanatges:no pollution, renewable,no fuel cosys and minimsl running costs

Disadvanatges:alters the habitat,prevents acces for boats,spoils the view

Tide barrages are big dams over rivers. As the tide comes in water allowed through the turbines ehich drives a generator producing electricity

Question 31

Advantages and disadvantages and how are bio-fuels used

Answer 31

Advantages: renewable,carbon neutral,reliable, crops take a short time to grow

Disadvanatges: cost to refine bio-fuel high,not enough space or water to meet demands, can’t respond to immediate demands

Bio-furels burnt to produce electricity or used to run vehicles in the same way as fossil fuels

Question 32

Examples of how non renewable resources can create environemntal problems

Answer 32

Coal,oil,gas release carbon dioixde in the atmosphere when burned adding to the greenhouse effect.

Burning coal and oil releases sulfur dioxide causing acid rain which is harmful to the ecosystem

Coal mining (open cast mining) makes a mess of the landscape

Oil spillages causes environmental problems effecting the environment

Nuclear fuel is clean but is very dangerous to dispose of may cause long term effects to the environment

Question 33

Energy use in the UK

Answer 33

Energy use in the UK has been deceraisng as more people are careful about enery use in homes and as appliances become more efficient.

Although fossil fuels are still the best way to gain energy to meet the demand however implementations of renewable resources are being used

Question 34

How are renewable resources being considered

Answer 34

People know the damages of fossil fuels to the environment. Pressure from other countries and the public has forced the governemnt to introduce targets for renewable resources.

Car companies are forced by the government to create more electric and hybrid cars as popularity for them increases

Question 35

What is the use of renewable resources being limited by

Answer 35

Mainly limited by the expensive cost to build renewble power plants (fossil fuels cost effective).

Ethical issues for paying for switch in renewable power

Ethical issues and protets of creating renewable plants (eyesore, noisy and destroys environment)

Some are not reelible enough (research to improve efficacy or use different renewable sources)

Personal changes for renwable resources still expensive