Physics Paper 1 (copy)

studied byStudied by 53 people
5.0(1)
Get a hint
Hint

Energy Stores

1 / 224

flashcard set

Earn XP

Description and Tags

225 Terms

1

Energy Stores

  1. Elastic potential

  2. Gravitational potential

  3. Thermal

  4. Electrostatic

  5. Nuclear

  6. Chemical

  7. Kinetic

  8. Magnetic

  9. Light

  10. Sound

New cards
2

How is energy transferred?

  1. Mechanically - force doing work

  2. Electrically - work done by moving charges

  3. Heating/Radiation - light, sound

New cards
3

How can work be done?

When a current flows or by a force moving an object

New cards
4

Kinetic energy formula

E=1/2mv² Kinetic energy(J) = 0.5 x mass(kg) x speed²(m/s)

New cards
5

Gravitational potential energy formula

E=mgh G.P.E(J) = mass(kg) x gravitational field strength (N/kg) x height (m)

New cards
6

What happens when an object falls and there's no air resistance?

Energy lost from the g.p.e store = energy gained in the kinetic energy store

New cards
7

What does air resistance do when acting against falling objects?

It causes some energy to be transferred to other energy stores e.g. the thermal energy stores of the object and the surroundings

New cards
8

Elastic potential energy formula

E=1/2ke² E.P.E(J) = 0.5 x spring constant(N/m) x extension²(m)

New cards
9

What is SHC?

The amount of energy needed to raise the temperature of 1kg of a substance by 1°C

New cards
10

SHC formula

E=mcθ Change in thermal energy(J) = mass(kg) x SHC(J/kg/°C) x temperature change(°C)

New cards
11

What is the conservation of energy principle?

Energy can be transferred usefully, or stored or dissipated (wasted energy), but can never be created or destroyed

New cards
12

What is power?

The rate of energy transfer, or the rate of doing work

New cards
13

What is 1W equal to?

1J of energy transferred per second

New cards
14

Power Equation 1

E=Pt Energy transferred(J) = power(W) x time(s)

New cards
15

Power Equation 2

W=Pt Work done(J) = power(W) x time(s)

New cards
16

What is conduction?

The process where vibrating particles transfer energy to neighbouring particles Energy is transferred to thermal stores of the object - this energy is shared across the kinetic energy stores

New cards
17

What is thermal conductivity?

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

New cards
18

What is convection?

Where energetic particles move away from hotter to cooler regions Energy is transferred to the thermal energy stores of the object and is shared across the kinetic stores

New cards
19

What do radiators create?

Convection currents

New cards
20

Convection currents - process

  1. Energy is transferred from the radiator to the nearby air particles by conduction

  2. The air by the radiator becomes warmer and less dense as the particles move quicker

  3. The warm air rises and displaces the cooler air, which is then heated by the radiator

  4. The previously heated air transfers energy to the surroundings - the air cools, becomes denser and sinks

New cards
21

What does lubrication do?

Reduce frictional forces

New cards
22

What does insulation do?

Reduce the rate of energy transfer by heating

New cards
23

Thermal insulation techniques

  1. Cavity walls - made up of an inner and outer wall with an air gap in the middle - the air gap reduces the amount of energy transferred by conduction through the walls

  2. Cavity wall insulators - the air gap is filled with foam also reduces energy transfer by convection in the wall cavity

  3. Loft insulation - reduces convection currents being created in lofts

  4. Double-glazed windows - air gap between two sheets of glass that prevent energy transfer by conduction through the windows

  5. Draught excluders - reduce energy transfers by convection around doors and windows

New cards
24

How do you improve efficiency?

  1. Lubrication

  2. Insulation

  3. Making objects more streamlined

New cards
25

Efficiency - energy transfer equation

Useful output energy transfer divided by total input energy transfer

New cards
26

Efficiency - power equation

Useful power output divided by total power input

New cards
27

Is any device 100% efficienct?

No

New cards
28

Where is wasted energy usually transferred?

Thermal energy stores

New cards
29

How do thick walls prevent energy losses through heating?

They're made from a material with a low thermal conductivity - the thicker the walls, the lower the thermal conductivity, the slower the rate of energy transfer

New cards
30

What objects are usually 100% efficient?

Electric heaters - all the energy in the electrostatic energy stores is transferred to useful thermal energy stores

New cards
31

Fossil fuels (coal, oil, natural gas)

Non-renewable Cause acid rain Cause global warming Reliable currently - they are finite, so they will run out eventually Coal mining ruins the landscape Oil spillages cause serious environmental problems

New cards
32

Energy resources used for transport

Petrol and diesel from oil - non-renewable Coal (steam trains) - non-renewable Bio-fuels - renewable

New cards
33

Energy resources used for heating

Natural gas - non-renewable Coal - non-renewable Electric heaters - non-renewable Geothermal - renewable Solar water heaters - renewable Bio-fuels - renewable

New cards
34

Wind Power

Renewable Doesn't cause global warming Doesn't cause acid rain No pollution No permanent damage to the landscape Free - initial costs are high Very noisy Spoil the view Not always reliable

New cards
35

Solar Power

Renewable Doesn't cause acid rain Doesn't cause global warming No pollution Free - solar panels are expensive though Not always reliable

New cards
36

Geothermal Power

Renewable Doesn't cause acid rain Doesn't cause global warming Free Very little damage to the environment Not very reliable - can only happen in certain places and there aren't very many of them

New cards
37

Hydroelectric Power

Renewable Reliable Doesn't cause acid rain Doesn't cause global warming No pollution Provides an immediate response to high demand Free - initial cost is high Big impact on environment and possible loss of habitat

New cards
38

Wave Power

Renewable Doesn't cause acid rain Doesn't cause global warming Free - initial costs are high Not always reliable - waves die out when the wind drops Disturbs the seabed and habitats of marine wildlife Spoils the view Hazard to boats

New cards
39

Tidal Power

Renewable Reliable Doesn't cause acid rain Doesn't cause global warming No pollution Free - initial costs are moderately high Spoils the view Alters the habitats of wildlife

New cards
40

Bio-fuels

Renewable Reliable Doesn't cause acid rain Carbon neutral Free Can cause global warming Loss of natural habitat from destruction of forests Cannot respond to immediate energy demands

New cards
41

Nuclear Power (Uranium or Plutonium)

Doesn't cause acid rain Doesn't cause global warming Reliable currently - finite Non-renewable High decommissioning costs Produces radioactive waste - no other pollution Nuclear waste is dangerous and hard to dispose of

New cards
42

Investigating Specific Heat Capacities - Method

  1. Measure the mass of a block with two holes in it, then wrap it in an insulating layer (e.g. newspaper) to reduce the energy transferred from the block to the surroundings. Insert the thermometer into one hole and the heater into another

  2. Measure the initial temperature of the block & set the potential difference of the power supply to be 10V. Turn on the power supply & start a stopwatch

  3. When you turn on the power, the current in the circuit does work on the heater, transferring energy electrically from the power supply to the heater's thermal energy stores - this energy is then transferred to the material's thermal energy store by heating, causing its temperature to increase

  4. As the block heats up, take readings of the temperature and current every minute for 10 minutes - the current shouldn't change

  5. Turn off the power supply. Use the measurements of the current & the p.d. to calculate the power supplied to the heater, thus calculating how much energy has been transferred to the heater at the time of each temperature reading

  6. If you assume all the energy supplied to the heater has been transferred to the block, you can plot a graph of energy transferred to the thermal energy store of the block against temperature

New cards
43

Investigating the Effectiveness of Materials as Thermal Insulators - Method

  1. Boil water in a kettle. Pour some of the water into a sealable container to a safe level. Measure the mass of water in the container

  2. Use a thermometer to measure the initial temperature of the water

  3. Seal the container & leave it for 5 minutes. Measure this time using a stopwatch

  4. Remove the lid & measure the final temperature of the water

  5. Pour away the water & allow the container to cool to room temperature

  6. Repeat this experiment, but wrap the container in a different material once it has been sealed. Ensure the mass of water is the same and so is the initial temperature each time

New cards
44

What is a closed system?

A system where neither matter nor energy can enter or leave

New cards
45

Why did electricity use in the 20th century increase?

  1. The population grew

  2. People began to use electricity for more & more things

New cards
46

Why did electricity use in the 21st century decrease?

  1. Appliances are becoming more efficient

  2. We're more careful with energy use in our homes

New cards
47

Why are we trying to increase our use of renewable energy resources?

  1. Burning fossil fuels is damaging to the environment

  2. Non-renewables will run out one day

  3. Pressure from other countries & the public has led to targets being set e.g the UK aims to use renewable resources to provide 15% of the total yearly energy by 2020

New cards
48

What has pressure from the public & other countries led to?

Pressure being put on energy providers to build new power plants that use renewable resources to ensure that they don't lose business & money

New cards
49

What is the use of renewables limited by?

  1. Reliability - since some energy resources aren't that reliable, a combination of different power plants would have to be used - expensive

  2. Money - building new power plants costs money, the cost of switching to renewable power will have to be paid & some people don't want to or can't afford to pay

  3. Politics - companies and governments can't force people to change their behaviour

New cards
50

What happens when a system changes?

Energy is transferred - it can be transferred into/away from the system, between different objects in the system or between different types of energy stores

New cards
51

Why are wind turbines unlikely to be able to power everything in the UK?

  1. Large numbers of turbines would need to be built - takes up space & is expensive

  2. Not always windy - the same amount of electrical power won't be produced every day

New cards
52

What is electric current?

The flow of electrical charge

New cards
53

What is electric current measured in?

Amps

New cards
54

What is potential difference?

Voltage - it pushes the electric charge around the circuit

New cards
55

What is potential difference measured in?

Volts

New cards
56

What is resistance?

Anything that slows the flow down

New cards
57

What is resistance measured in?

Ohms

New cards
58

The greater the resistance...

...the smaller the current that flows

New cards
59

What is the formula for charge?

Charge (coulombs) = current (amps) x time (seconds) Q=It

New cards
60

What is the formula for Pd?

Potential difference (volts) = Current (amps) x Resistance (ohms) V=IR

New cards
61

The longer the wire...

...the greater the resistance

New cards
62

Is the ammeter placed in series or parallel?

Series

New cards
63

Is the voltmeter placed in series or parallel?

Parallel

New cards
64

Do Ohmic Conductors have a constant resistance?

Yes - at a constant temperature, the current is directly proportional to the potential difference

New cards
65

What does resistance change in?

Diodes and filament lamps

New cards
66

Why does resistance increase with temperature in a filament lamp?

When the electrical charge flows through the lamp, it transfers some energy to the thermal energy stores of the filament which is designed to heat up. Therefore, the resistance, temperature and current all increase Resistance is directly proportional to temperature

New cards
67

What is an LDR?

Light Dependent Resistor - a resistant dependent on the intensity of light In bright light, the resistance decreases In darkness, the resistance is highest

New cards
68

What is a thermistor?

A temperature dependent resistor In hot conditions, the resistance decreases In cold conditions, the resistance increases

New cards
69

What happens to Pd in a series circuit?

It's shared between all the components

New cards
70

What happens to current in a series circuit?

The current is the same in all components

New cards
71

What happens to resistance in a series circuit?

The total resistance is the sum of all the resistances

New cards
72

What happens to Pd in a parallel circuit?

The Pd is the same in all components

New cards
73

What happens to current in a parallel circuit?

The current is shared between the components, therefore the total current is found by adding up the currents of all the components

New cards
74

What happens to resistance in a parallel circuit?

If you have two resistors parallel, their total resistance is less than the resistance of the smallest of the two resistors

New cards
75

Mains supply is...

AC - Alternating current

New cards
76

Battery supply is...

DC - Direct Current

New cards
77

Alternating Current

The current is constantly changing direction Alternating currents are produced by alternating voltages in which the positive and negative ends keep alternating

New cards
78

UK Mains Supply Voltage

230V

New cards
79

UK Frequency of AC

50Hz (hertz)

New cards
80

Direct Current

Current is always flowing in the same direction Created by a direct voltage

New cards
81

Live Wire

Brown colour Bottom right of the three pin plug Provides the alternating pd from the mains supply - 230V Current flows in through this wire

New cards
82

Neutral Wire

Blue colour Bottom left of the three pin plug Completes the circuit and carries away current Electricity flows out through this wire Around 0V

New cards
83

Earth Wire

Green and yellow colour Middle of the three pin plug Protects the wiring Stops the casing from becoming live Doesn't usually carry a current - only when there's a fault Around 0V

New cards
84

Equation - Energy transferred 1

Energy transferred (J) = Power (W) x Time (s) E=Pt

New cards
85

A 600W microwave is used for 5 minutes. How long (in minutes) would a 750W microwave take to do the same amount of work

  1. 600 x (5 x 60) = 180,000J or 180kJ

  2. 180,000J = 750W x t

  3. t = 180,000J/750W

  4. t = 240s = 4 minutes

New cards
86

The lower the power rating...

...The less electricity an appliance uses in a given time, therefore it is cheaper to run

New cards
87

Equation - Energy Transferred 2

Energy transferred (J) = Charge flow (C) x Potential difference (V) E=QV

New cards
88

The motor in an electric toothbrush is attached to a 3V battery. 140C of charge passes through the circuit as it is used. Calculate the energy transferred

  1. E=QV

  2. E= 140C x 3V

  3. E = 420J

New cards
89

Equation - Power 1

Power (W) = Potential difference (V) x Current (A) P=VI

New cards
90

Equation - Power 2

P=I²xR Power = current² x resistance

New cards
91

A 1.0kW hair dryer is connected to a 230V supply. Calculate the current through the hair dryer. Give your answer to two significant figures

I=P/V I= 1000/230 I=4.3A

New cards
92

What is the National Grid?

A giant system of cables and transformers that covers the UK and connects power stations to consumers

New cards
93

When does demand for electricity increase?

When it starts to get dark or cold outside When people get up in the morning When people come home from school or work

New cards
94

What is the problem with a high current?

You lose loads of energy as the wires heat up and energy is transferred to the thermal energy stores of the surroundings

New cards
95

What's the cheaper way of transmitting power?

High potential difference and low current - decreases the energy lost by heating the wire and the surroundings

New cards
96

How is static electricity caused?

Friction - when two things rub against each other, electrons from one will rub off on to the other One material will have a positive static charge (e.g. acetate) and the other will have a negative static charge (e.g. polythene)

New cards
97

What subatomic particle moves?

Electrons Positive charges never move - a positive charge is achieved when electrons move away

New cards
98

What increases with a build up of electric charge?

The potential difference between the object and the earth

New cards
99

What is the spark?

When the electrons jump across the gap between the charged particle and the earth if the potential difference becomes too large

New cards
100

How big is the gap for the spark to happen?

Usually fairly small (lightning is an exception)

New cards

Explore top notes

note Note
studied byStudied by 11 people
... ago
5.0(1)
note Note
studied byStudied by 23 people
... ago
5.0(1)
note Note
studied byStudied by 52 people
... ago
4.7(3)
note Note
studied byStudied by 2 people
... ago
4.0(1)
note Note
studied byStudied by 13 people
... ago
5.0(1)
note Note
studied byStudied by 35 people
... ago
5.0(1)
note Note
studied byStudied by 9 people
... ago
5.0(1)
note Note
studied byStudied by 448 people
... ago
5.0(1)

Explore top flashcards

flashcards Flashcard (68)
studied byStudied by 3 people
... ago
5.0(1)
flashcards Flashcard (30)
studied byStudied by 5 people
... ago
5.0(1)
flashcards Flashcard (182)
studied byStudied by 28 people
... ago
5.0(3)
flashcards Flashcard (22)
studied byStudied by 5 people
... ago
5.0(1)
flashcards Flashcard (30)
studied byStudied by 2 people
... ago
5.0(1)
flashcards Flashcard (50)
studied byStudied by 13 people
... ago
5.0(1)
flashcards Flashcard (40)
studied byStudied by 2 people
... ago
5.0(1)
flashcards Flashcard (40)
studied byStudied by 1 person
... ago
5.0(1)
robot