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Yr 10 Mock > Physics > Flashcards

Physics Flashcards

1
Q

How many energy stores are there?

A

8

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2
Q

Name all 8 energy stores

A

Kinetic, thermal, gravitational potential energy, elastic potential energy, electrostatic, magnetic, chemical and nuclear

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3
Q

What is the kinetic energy equation?

A

Kinetic Energy = 1/2 x Mass x Velocity^2

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4
Q

How is KE transferred to an object?

A

When the object speeds up

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5
Q

How is KE transferred from an object?

A

When the object slows down

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6
Q

What are two factors that affects the KE of an object?

A

It’s mass and it’s velocity

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7
Q

What would happen to the KE of an object if you were to double it’s speed?

A

The speed would increase by a factor of 4

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8
Q

What is the gravitational potential equation?

A

Gravitational Potential = Mass x Gravity x Height

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9
Q

Define conservation of energy

A

Energy an be stored, transferred between stores and dissipated - but it can never be created or destroyed. Therefore, the total energy of a closed system has no net change

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10
Q

What are the four ways energy can be transferred?

A

Radiation, heating, electrically and mechanically

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11
Q

Define energy transfer by radiation?

A

Energy transferred by waves

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12
Q

Define energy transfer by heating?

A

Energy transferred from a hotter object to a colder object

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13
Q

Define energy transfer by electrically?

A

A charge doing work

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14
Q

Define energy transfer by mechanically?

A

A force acting on an object

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15
Q

Give an example of energy transfer by radiation

A

Energy from the Sun reaching Earth by light

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16
Q

Give an example of energy transfer by heating

A

Heating a pan on a hob

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17
Q

Give an example of energy transfer electrically

A

Charges moving around a circuit

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18
Q

Give an example of energy transfer mechanically

A

Pushing, stretching or squashing an object

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19
Q

Define useful energy

A

Energy transferred from a store to a useful store

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20
Q

What is the efficiency equation?

A

Efficiency = Useful Energy / Total Energy

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21
Q

What are methods of reducing wasted energy?

A

Lubrication or thermal insulation

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22
Q

How does lubrication reduce wasted energy?

A

By reducing friction

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23
Q

What type of energy transfer is friction?

A

Mechanical (Kinetic -> Thermal)

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24
Q

How does insulation reduce wasted energy?

A

By reducing release of thermal energy

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25
Q

Describe the process of conduction

A

Particles are heated, making them hotter
Particles vibrate more and collide with each other
This transfers energy from their KE stores to other particles which then vibrate faster

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26
Q

What does conduction do?

A

Transfers energy through objects

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27
Q

What does thermal conductivity describe?

A

How well a material transfers energy by conduction

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28
Q

Give an example of a type of material with a high thermal conductivity

A

Metals (Copper)

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29
Q

Give an example of a material with a low thermal conductivity

A

Gases (Air)

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30
Q

What are ways a house is designed to reduce thermal conductivity?

A

Double-glazing windows
Cavity walls
Thick walls

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31
Q

How does the thickness of a wall affect the rate of energy transfer?

A

The thicker the wall, the slower the rate of energy transfer

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32
Q

What is an example of a non-renewable fuel?

A

Fossil fuels and nuclear fuels

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33
Q

Describe the cost of afossil fuel plant?

A

Relatively cheap

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34
Q

Describe the cost of a nuclear power plant?

A

Very costly

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35
Q

What are the disadvantages of non-renewable usage?

A

Contribution to greenhouse effect
Oil spillages
Risk of nuclear explosion

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36
Q

List examples of renewable energy sources?

A 
Bio-fuels
Wind Power
Solar Power
Hydro-electric Power
Tidal Power
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37
Q

What is an advantage of using renewable energy sources?

A

Don’t damage the environment as much as non-renewable sources

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38
Q

What is a disdvantage of using renewable energy sources?

A

Don’t release as much energy and not reliable as some depend on the weather

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39
Q

What are biofuels?

A

Renewable energy resources created from either plant products or animal dung

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40
Q

Why is it arguably carbon neutral?

A

If you plant trees at the rate you’re burning them

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41
Q

What are the advantages of biofuel?

A

Reliable

Short time to grow

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42
Q

What are the disadvantages of biofuel?

A

Can’t respond to immediate energy demands
Very high to refine the fuels
Wasting resources for plants grown for food (water and space)

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43
Q

What are the advantages of wind power?

A

Low running costs

No pollution

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44
Q

What are the disadvantages of wind power?

A 
Expensive to setup
Unsightly and noisy
Less efficient than non-renewable
Can't respond to high demand
Unreliable
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45
Q

What are solar cells made from?

A

Materials that use energy transferred by light to create and electric current

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46
Q

What are the advantages of solar power?

A

No running costs

No pollution

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47
Q

What are the disadvantages of solar power?

A

Expensive to setup
Doesn’t work at night
Can’t respond to high demand

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48
Q

What does HEP usually involve?

A

Flooding a valley

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49
Q

What are the advantages of HEP?

A

Immediately respond to increased electricity demand
Low running costs
Reliable
No pollution

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50
Q

What are the disadvantages of HEP?

A

Loss of habitats
Risk of flooding
Expensive to setup

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51
Q

How does tidal power work?

A

Tide come’s in to fill up the estuary

Water is then let out through turbines which generates electricity

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52
Q

What are the advantages of tidal power?

A

No pollution
Reliable
No fuel costs
Low running costs

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53
Q

What are the disadvantages of tidal power?

A

Affects boat access
Spoils the view
Loss of habitats
Moderately high setup cost

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54
Q

What is most of the UK’s energy produced from?

A

Non-renewable

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55
Q

Why are smaller energy providers reluctant to change energy source?

A

It costs money to invest in renewable energy

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56
Q

Why is research into improving the reliability and cost of renewable resources bad?

A

Costs time and money

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57
Q

Why are personal changes hard to achieve?

A

Expensive

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58
Q

What do waves transfer?

A

Energy and infomation

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59
Q

What is the amplitude of a wave?

A

The displacement from the rest position to a crest

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60
Q

What is the wavelength of a wave?

A

The length of a full cycle of the wave

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61
Q

What is the frequency of a wave?

A

The number of complete cycles of the wave passing a certain point per second

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62
Q

What is frequency measure in?

A

Hertz

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63
Q

What does hertz actually equal?

A

One wave per second

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64
Q

What is the period of a wave?

A

The number of seconds it takes for one full cycle

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65
Q

How do you calculate the period of a wave?

A

Period = 1 / Frequency

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66
Q

Describe the direction of a transverse wave

A

Perpendicular to the direction the wave travels

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67
Q

Describe the direction of a longitudinal wave

A

Parallel to the direction the wave travels

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68
Q

Give some examples of transverse waves

A

Electromagnetic waves
S-waves
Ripples and waves in water

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69
Q

Give some examples of longitudinal waves

A

Sound waves

P-waves

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70
Q

How do longitudinal waves actually move?

A

By making compressions (high pressure) and rarefactions (low pressure)

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71
Q

In terms of longitudinal waves, describe compressions

A

High pressure and lots of particles

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72
Q

In terms of longitudinal waves, describe rarefactions

A

Low pressure and few particles

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73
Q

What is the wave speed equation?

A

Wave Speed = Distance / Time
Or
Wave Speed = Wavelength x Frequency

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74
Q

What can you use to measure the speed of sound?

A

An oscilloscope

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75
Q

Describe how to use an oscilloscope to measure the speed of sound

A

Line up the microphones so waves align but have moved exactly one wavelength apart
Measure the distance between the microphones to find one wavelength

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76
Q

What can you use to measure the speed of water ripples?

A

A strobe light

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77
Q

Describe how to use a strobe light to measure the speed of water ripples

A

Use signal generator to set water waves to a certain frequency
Alter the frequency of the strobe light until the wave pattern on the screen appears to freeze
Then measure the distance between lines that are 10 wavelengths apart then find the average wavelength

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78
Q

What can you use to measure the speed of waves in solids?

A

Peak Frequency

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79
Q

Describe how to use peak frequency to find the speed of waves in solids

A

Measure and record the length of a metal rod
Tap the rod with a hammer and write down the peak frequency displayed by the computer
Repeat this three times to get an average peak frequency
Calculate the speed using V = fλ (λ = twice the length of the rod)

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80
Q

What three things can occur when a wave hits a boundary?

A

Absorbed, transmitted or reflected

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81
Q

What happens to wave when it’s absorbed?

A

The wave transfers energy to the material’s stores

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82
Q

What happens to wave when it’s transmitted?

A

The wave carries on travelling through the new material

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83
Q

What happens to wave when it’s reflected?

A

The wave is sent back away from the second material

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84
Q

How does different density materials affect wave speed?

A

The denser the material, the slower the wave

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85
Q

What happens to a wave when it hits a boundary at an angle?

A

Speed and direction changes

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86
Q

What happens to a wave when it hits a boundary along the normal?

A

Speed change but no change in direction

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87
Q

How does change in speed affect how much a wave bends?

A

The greater the change in speed, the more a wave bends

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88
Q

When will a wave refract towards the normal?

A

If it slows down

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89
Q

When will a wave refract away from the normal?

A

If it speeds up

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90
Q

What affects how much a wave will refract?

A

It’s wavelength, shorter wavelengths bend more

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91
Q

What doesn’t change during refraction?

A

A wave’s frequency

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92
Q

What does change during refraction?

A

A wave’s speed and wavelength

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93
Q

What is the normal?

A

A line that is at 90* to the boundary

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94
Q

What causes sound waves?

A

Vibrating objects

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95
Q

What determines what an object can transmit?

A

It’s size, shape and structure

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96
Q

How are the vibrations in a sound wave passed through?

A

By a series of compressions and rarefactions

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97
Q

True or False? Sound travels at different speeds in different media?

A

True

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98
Q

Compare the speed of sound waves in all three of the states of matter?

A

Solid > Liquid > Gas

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99
Q

Why can’t sound waves travel in space?

A

Because there are no particles to move or vibrate

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100
Q

Describe how the ear detects sound?

A

Sound enters eardrum causing it to vibrate
Vibrations passed along to ossicles through the semicircular canals and to the cochlea
Cochlea turns these signals into electrical signals which get sent to your brain

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101
Q

How does frequency affect pitch?

A

A higher frequency means a higher pitch

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102
Q

What limits the human hearing?

A

Size and shape of the eardrum

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103
Q

What is ultrasound?

A

A sound with frequencies higher than 20,000Hz

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104
Q

True or False? Ultrasound is the lowest possible frequency a human can hear?

A

False

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105
Q

What happens when an ultrasound hits a boundary?

A

It gets partially reflected

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106
Q

What is partial reflection?

A

When a wave passes from one medium to another, some of the wave is reflected off the boundary and some is transmitted

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107
Q

What are uses of ultrasound?

A

Medical imaging and industrial imaging

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108
Q

How is ultrasound used in medical imaging?

A

Ultrasound waves can pass through the body but whenever they reach a boundary some of the wave is reflected back and detected
The exact time and distribution of these echoes are processed by a computer to produce a videoo image of the foetus

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109
Q

How safe is ultrasound?

A

As far as we know, it’s completely safe

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110
Q

How is ultrasound used in industrial imaging?

A

Ultrasound can also be used to find flaws in objects
Ultrasound waves entering a material will usually be reflected
If there is a flaw, the waves will be reflected soon

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111
Q

In sonar, how do you calculate the distance the wave has travelled?

A

Distance = Speed x Time

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112
Q

In sonar, how do you calculate the depth of the sea?

A

Distance = (Speed x Time) / 2

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113
Q

What is infrasound?

A

A sound with frequencies lower than 20

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114
Q

Name some examples of animals that communicate using infrasound

A

Elephants and whales

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115
Q

Name some uses of infrasound

A

Animal communication and natural disaster detection

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116
Q

What causes seismic waves?

A

Earthquakes and explosions

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117
Q

Name two seismic waves

A

P-waves and S-waves

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118
Q

What can scientists understand through seismic waves?

A

The structure of the Earth

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119
Q

What type of wave is a P-wave?

A

Longitudinal

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120
Q

What state can P-wave’s travel through?

A

Solids and liquids

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121
Q

Describe the speed of a P-wave?

A

Faster than S-waves

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122
Q

What type of wave is a S-wave?

A

Transverse

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123
Q

What state can S-wave’s travel through?

A

Solid

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124
Q

Describe the speed of a S-wave?

A

Slower than P-waves

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125
Q

True or False? The angle of incidence = Angle of reflection - 180?

A

False, angle of incidence = angle of reflection

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126
Q

State the law of reflection

A

Angle of incidence = Angle of reflection

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127
Q

What is the angle of incidence?

A

The angle between the incoming wave and the normal

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128
Q

What is the angle of reflection?

A

The angle between the reflected wave and the normal

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129
Q

What is the normal?

A

An imaginery line that’s perpendicular to the surface at the point of incidence

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130
Q

What is total internal reflection?

A

When a wave is reflected back into the material

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131
Q

When can TIR occur?

A

More dense material towards a less dense

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132
Q

When does TIR occur?

A

When the critical angle is exceeded

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133
Q

What is the critical angle?

A

The angle of incidence beyond which rays of light passing travel perpendicular to the normal (parallel to the normal)

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134
Q

What are the two types of reflection?

A

Specular and diffuse

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135
Q

When does specular reflection occur?

A

When waves are reflected in a single direction by a smooth surface

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136
Q

When does diffuse reflection occur?

A

When waves are reflected by a rough surface and the waves are reflected in all directions

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137
Q

Why does diffuse reflection occur?

A

Because the normal is different for each incident ray so each ray has a different angle of incidence and because of angle of incidence = angle of reflection the angle of reflection is different aswell

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138
Q

What do you do with the glass block when investigating refraction?

A

Trace around it and use a ray box to shine light through it

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139
Q

Once the glass block has refracted the light, what do you do?

A

Trace the incident ray and the emergent ray and then join up the rays with a straight line

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140
Q

Once all the rays are drawn, when investigating refraction, what do you do next?

A

Use a protractor to measure the angles and repeat whole experiment and calculate an average

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141
Q

What should you see when investigating refraction?

A

Ray bends towards normal on entry of the glass and then bends away from the normal on exit of the glass

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142
Q

What does the colour and transparency of a colour depend on?

A

The wave’s absorbed wavelength

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143
Q

What do opaque objects not do?

A

Transmit light

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144
Q

What do transparent objects do?

A

Transmit light

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145
Q

What do translucent objects do?

A

Absorb and reflect light

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146
Q

How do colour filters work?

A

They only let through particlular wavelengths of light

147
Q

What are colour filters used to?

A

Filter out different wavelengths of light, so that only certain colurs are transmitted

148
Q

How do secondary colour filters work?

A

They allow both primary colours that make that colour through

149
Q

Name the two types of lens

A

Diverging and converging

150
Q

Describe the shape of a converging lens

A

Bulges outwards in the middle

151
Q

Describe the shape of a diverging lens

A

Caves inward

152
Q

What does a converging lens do?

A

Causes parallel rays of light to be brought together at the principal focus

153
Q

What does a diverging lens do?

A

Causes parallel rays of light to spread out

154
Q

Where is the principal focus in a converging lens?

A

Where rays hitting the lens parallel to the axis all meet

155
Q

Where is the principal focus in a diverging lens?

A

Where rays hitting the lens parallel to the axis appear to all come from

156
Q

What is the focal length?

A

The distance from the centre of the lens to the principal focus

157
Q

What is a virtual image?

A

An image that is created when light rays appear to be coming from a completely different place to where they’re actually coming from

158
Q

What is a real image?

A

An image that is created when light rays come together to form an image

159
Q

What image can be captured on a screen?

A

Real

160
Q

What image can’t be captured on a screen?

A

Virtual

161
Q

What increases the power of a lens?

A

It’s curvature

162
Q

What lens has a postive power?

A

Converging

163
Q

What lens has a negative power?

A

Diverging

164
Q

What does a stronger lens mean?

A

The more strongly it converges rays of light

165
Q

True or False? Some materials are better at focusing light than others?

A

True

166
Q

On a ray diagram, what does a diverging lens look like?

A

>

167
Q

On a ray diagram, what does a converging lens look like?

A
168
Q

On a diverging lens diagram, how do you locate the virtual image?

A

Mark the point where the virtual ray meets the ray that goes through the middle

169
Q

What type of waves are EM waves?

A

Transverse

170
Q

True or False? EM waves all travel the same speed everywhere?

A

False, although they travel at the same speed in a vaccum, they travel at different speeds in different materials

171
Q

How are EM waves generated?

A

By changes in atoms and it’s nuclei

172
Q

How are gamma rays created?

A

When a positron collides with an electron

173
Q

How are visible light rays created?

A

Change in electron energy levels

174
Q

What do all EM waves transfer?

A

Energy from a source to an absorber

175
Q

How do you increase the amount of energy an EM wave transfers?

A

By increasing the frequency

176
Q

How do radio waves interact with the human body?

A

Transmits through without being absorbed

177
Q

How do micro waves interact with the human body?

A

Some transmits, however some is absorbed causing the heating of cells

178
Q

How do visible and infared waves interact with the human body?

A

Mostly reflected or absorbed by the skin, however, if too much can burn the skin

179
Q

How do ultraviolet waves interact with the human body?

A

Is absorbed by the skin, however, due to it’s higher frequency it is dangerous (carcinogenic)

180
Q

How do x-ray and gamma waves interact with the human body?

A

Either reflected, transmitted or absorbed as it depends on the deepness of the tissue and can cause mutations and damage to cells

181
Q

True or False? Only certain objects emit EM radiation, this is because not all atoms are unstable?

A

False, all objects absorb and emit EM radiation

182
Q

What does the distribution and intensity of the EM emitted depend on?

A

The objects temperature

183
Q

How does temperature change the EM wave emitted?

A

The hotter the object, the more intense the emitted wavelength

184
Q

What happens to the radiation emitted to the Earth from the Sun?

A

Some of it is reflected but most of it is absorbed

185
Q

Why does it get colder at night?

A

Because Earth emits it’s radiation which causes a decrease in temperature

186
Q

How do you investigate what surfaces/colour are better emitters?

A

Wrap test tubes in the same material but with a different colour or surface
Add boiling water to the test tubes (same volume)
Measure temp (thermometer)
Temperature that drops the most will be best emitter

187
Q

What are EM waves made up of?

A

Oscillating electric and magnetic fields

188
Q

Name one thing made up of oscillating electric charges?

A

Alternating currents

189
Q

How can you produce EM waves with an AC?

A

Make transmitter oscillate to create the radio waves
Reciever absorbs radio waves, energy carried by the waves are transferred to the electrons in the circuit
The current will have the same frequency as the radio wave that generated it (and vice versa)

190
Q

What is the main use for radio waves?

A

Communication and broadcasting

191
Q

Compare long-wave to short-wave radio

A

Long-wave radio can be recieved halfway around the world this is because they can bend around the curved surface of Earth
Short-wave radio can be recieved from long distances aswell, however, this is because they are reflected by the Earth’s atmosphere

192
Q

How does bluetooth work?

A

By sending short-wave radio waves

193
Q

What type of waves do TV and FM radio use?

A

Very short radio waves

194
Q

What do satellites use to communicate?

A

EM waves

195
Q

How does a satellite work to transmit TV?

A

TV sends it’s signal into space where the satellite picks it up and reflects it back to Earth where a satellite dish recieves it

196
Q

How do microwave ovens work?

A

By transmitting microwaves that are absorbed by the water molecules in food which then heats the food

197
Q

How are the microwaves in a microwave different to satellites?

A

Microwaves in satellites need to pass through the Earth’s watery atmosphere whilst microwaves in microwaves need to transmit through the food a bit and then be absorbed

198
Q

What are some uses of IR radiation?

A

To monitor temperature, security systems and transmit infomation

199
Q

How does IR radiation monitor temperature?

A

It detects the radiation and transmits it into an electrical signal

200
Q

How can IR radiation be used to heat foods?

A

Object emits IR which then transfers into the thermal energy in the object that is being heated

201
Q

Give some uses of IR radiation when transfering infomation

A

Optical fibers and TV remotes

202
Q

What do optical fibers use?

A

Total Internal Reflection

203
Q

Give uses of visible light

A

Photography and vision

204
Q

Give uses of ultraviolet waves

A

Fluorescent lights, security pens and the sterilising of water

205
Q

Give uses of x-rays

A

Medical imaging and airport security

206
Q

Why can x-rays be used to “see-through” objects?

A

Because x-rays are transmitted by flesh but absorbed by denser material (bones or metal)

207
Q

Give uses of gamma rays

A

Sterilising, medical imaging and cancer treatment

208
Q

Why are gamma rays used to sterilise stuff?

A

Because the gamma rays kill microbes

209
Q

Why are gamma rays used to treat cancer?

A

The radiation can be targeted to kill cancer cells

210
Q

Define a scalar

A

A quantity with only magnitude, not direction.

211
Q

Define a vector

A

A quantity with magnitude and direction

212
Q

What is the difference between a scalar and a vector?

A

A scalar has only magnitude and no direction whilst a vector has magnitude and direction

213
Q

Give examples of a scalar quantity

A

Speed and distance

214
Q

Give examples of a vector quantity

A

Velocity and displacement

215
Q

What is the acceleration equation?

A

Acceleration = Change in velocity / Time

216
Q

What is the uniform acceleration equation?

A

Final velocity - Inital velocity = 2 x Acceleration x Distance

217
Q

What does the gradient equal in a distance time graph?

A

The speed of the object

218
Q

What does a flat section equal in a distance time graph?

A

Where the object has stopped

219
Q

What does a curve equal in a distance time graph?

A

Where the object is accelerating

220
Q

What does the gradient equal in a speed time graph?

A

The acceleration of the object

221
Q

What does a flat section equal in a speed time graph?

A

Steady speed

222
Q

What does a uphill equal in a speed time graph?

A

Acceleration

223
Q

What does a downhill equal in a speed time graph?

A

Deceleration

224
Q

What does the area under the graph equal in a speed time graph?

A

The distance covered

225
Q

What is newtons first law?

A

If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it’ll just carry on moving at the same velocity

226
Q

What is newtons second law?

A

The larger the resultant force acting on an object, the more the object accelerated (Force = Mass x Acceleration)

227
Q

What is newtons third law?

A

Whenever two objects interact, they exert equal and opposite forces on each other (every action has an equal and opposite reaction)

228
Q

Why are large decelerations of objects dangerous?

A

High force required (F=ma)

229
Q

How can you reduce the risk during large decelerations?

A

By increasing time (decreasing deceleration)

230
Q

Give examples of how a car reduces large decelerations?

A

Seat belts stretch, crumple zones and air bags

231
Q

Define mass

A

The amount of matter in an object

232
Q

What type of quantity is mass?

A

Scalar

233
Q

Define weight

A

The force acting on an object due to gravity

234
Q

What type of quantity is weight?

A

Vector

235
Q

What are the units for mass?

A

Grams

236
Q

What are the units for weight?

A

Newtons

237
Q

What is the equation for weight?

A

Weight = Mass x Graviational Field Strength

238
Q

How does distance from an object affect graviational field strength?

A

The closer you are to the mass, the stronger the graviational field strength

239
Q

When an object is travelling in a circular motion, what remains the same?

A

The objects speed

240
Q

When an object is travelling in a circular motion, what changes constantly?

A

The objects velocity (direction)

241
Q

When an object is travelling in a circular motion, where does the force act towards?

A

The centre of the circle

242
Q

When investigating the motion of a trolley on a ramp, what do you measure the mass of?

A

The trolley, the unit masses and the hook

243
Q

When investigating the motion of a trolley on a ramp, what do you measure the length of?

A

The piece of card which interupts the light gate beams

244
Q

What is inertia?

A

The tendency for motion to remain unchanged

245
Q

What does an object’s inertial mass measure?

A

How difficult it is to change the velocity of an object

246
Q

Why do objects move although ‘equal and opposite reactions’?

A

Depends on the mass as (Force / Mass = Acceleration)

So less mass will have a greater acceleration

247
Q

What is momentum

A

The amount of oomph an object has

248
Q

Define momentum

A

The product of the object’s mass and velocity

249
Q

What is the equation for momentum?

A

Momentum = Mass x Velocity

250
Q

How does the mass of an object affect its momentum?

A

The higher the mass, the larger the momentum

251
Q

How does the velocity of an object affect its momentum?

A

The higher the velocity, the larger the momentum

252
Q

What type of quantity is momentum?

A

Vector

253
Q

What is conservation of momentum?

A

In a closed system, the total momentum before an event is the same as after the event

254
Q

If an object has zero velocity, what is it’s momentum?

A

Zero (Anything times 0 is 0)

255
Q

What causes changes in momentum?

A

Forces

256
Q

What is the equation for change in momentum?

A 
Force = Change in momentum / Time
Force = Mass x (Final Velocity - Inital Velocity) / Time
257
Q

What is the equation for stopping distance?

A

Stopping Distance = Thinking Distance + Braking Distance

258
Q

What is the thinking distance?

A

The distance the car travels in the driver’s reaction time

259
Q

What is the drivers reaction time?

A

The time between noticing the hazard and applying the breaks

260
Q

What affects the thinking distance?

A

Speed and reaction time (tiredness, drugs and alcohol)

261
Q

What is the braking distance?

A

The distance taken to stop once the brakes have been applied

262
Q

What affects the braking distance?

A

Speed, mass, condition of brakes and the friction between the car and the road

263
Q

When measuring reaction times with a ruler, how do you compare results?

A

The longer the distance, the longer the reaction time

264
Q

When measuring reaction times with a ruler, why should you do lots of repeats?

A

Test is extremely inaccurate

265
Q

What is the reaction time of a typical driver?

A

One second

266
Q

To avoid an accident, what must drivers do?

A

Leave enough space in front so they could stop safely (at least more than the stopping distance)

267
Q

Why are speed limits important?

A

Because speed affects stopping distances alot

268
Q

How does speed affect thinking distance?

A

As speed increases, thinking distance increases at roughly the same rate (reaction time stays roughly the same)

269
Q

How does speed affect braking distance?

A

If speed is times by 2, braking distance will be times by 4 (2²)

270
Q

What is the equation for work done by the brakes?

A

Braking force x Braking distance = 1/2x(Mass x Velocity²)

271
Q

What do electrons sit in?

A

Different energy levels (shells)

272
Q

How can a inner electron move to a higher energy level?

A

By absorbing electromagnetic radiation with the right amount of energy

273
Q

What has happened when an electron is ‘excited’?

A

It has moved up to an empty or partially filled shell

274
Q

What will happen after an electron becomes ‘excited’?

A

The electron will quickly fall back to its original energy level and in doing so will emit the same amount of energy absorbeb

275
Q

How is the energy carried away when an electron moves back to it’s original energy level?

A

By an electromagnetic wave

276
Q

What does the part of the electromagnetic wave emitted depend on?

A

The energy

277
Q

As you get further from the nucleus what happens to the levels?

A

They get closer together

278
Q

What happens when an atom is ionised?

A

It loses an electron (Atom is now positively charged)

279
Q

What ionises atoms?

A

Ionising radiation

280
Q

What is ionising radiation?

A

Any radiation that can knock electrons from atoms

281
Q

What are isotopes?

A

Different forms of the same element

282
Q

What do unstable isotops do?

A

Radioactive decay

283
Q

Why do unstable isotops radioactively decay?

A

Because they attempt to become stable

284
Q

What do radioactive substances spit out?

A

Alpha, beta and gamma radiation but also neutrons

285
Q

What are alpha particles?

A

Helium Nuclei (2 protons + 2 neutrons)

286
Q

How penetrative is alpha radiation?

A

Not very

287
Q

What stops alpha radiation?

A

5 cm of air or a thin sheet of paper

288
Q

Why is alpha radiation extremely ionising?

A

Because of its size

289
Q

What are beta particles?

A

Either a fast-moving electron or a fast-moving positron

290
Q

How penetrative is beta radiation?

A

Moderately

291
Q

What stops beta radiation?

A

Meters of air or a sheet of aluminium

292
Q

Which type of beta radiation has a shorter range?

A

Positive because it contains positrons and when they hit an electron they destroy each other and produce gamma rays

293
Q

What are gamma rays?

A

High frequency, low wavelength electromagnetic wavess

294
Q

How penetratative is gamma radiation?

A

Extremely as they penetrate far into materials without being stopped

295
Q

What stops gamma radiation?

A

Thick sheets of lead or meters of concrete

296
Q

When is gamma radiation created?

A

When a nucleus decays and it undergoes nuclear rearrangement and releases energy

297
Q

What are nuclear equations ways of showing?

A

Radioactive decay

298
Q

How are nuclear equations written?

A

Atom before decay -> Atom after decay + Radiation emitted

299
Q

What is the one ‘golden rule’ with nuclear equations?

A

The total mass and atomic numbers must remain equal on both sides

300
Q

How does alpha decay affect the atom?

A

Decreases the charge and mass of the nucleus (by 2 and then 4)

301
Q

How does beta-minus decay affect the atom?

A

Increases the charge of the nucleus

302
Q

How does beta-plus decay affect the atom?

A

Decreases the charge of the nucleus

303
Q

How does neutron emission affect the atom?

A

Decreases the mass of the nucleus

304
Q

How are beta-minus particles formed?

A

A neutron turns into an electron and proton

Electron then leaves nucleus

305
Q

How are beta-plus particles formed?

A

A proton turns into an neutron and positron

Positron then leaves nucleus

306
Q

True or False? Radioactivity is a totally random process?

A

True

307
Q

What do radioactive sources contain?

A

Radioactive isotopes that give out radiation from the nuclei of their atoms

308
Q

What is activity?

A

The rate at which a source decays

309
Q

What are the units for activity?

A

Becquerels (Bq)

310
Q

What does 1 becquerel equal?

A

1 decay per second

311
Q

How can you measure activity?

A

By using a Geiger-Muller tube and counting the amount of clicks

312
Q

What happens each time a radioactive nucleus decays?

A

One more radioactive nucleus disappears which causes the activity as a whole to decrease

313
Q

What is half-life?

A

The average time taken for the numer of radioactive nuclei in an isotope to halve

314
Q

What does a short half-life mean?

A

The activity falls quickly

315
Q

What does a long half-life mean?

A

The activity falls slowly

316
Q

Where does background radiation come from?

A

Human activity, space, food, buildings and rocks

317
Q

What is the absorbed radiation dose?

A

The amount of radiation you’re exposed to

318
Q

What are ways of reducing irradiation?

A

Lead-lined boxes, barriers and remote-controlled arms

319
Q

Why is contamination of unwanted radioactive atoms bad?

A

If they get stuck, they will decay and release radiation

320
Q

When are contaminated people at risk of harm?

A

Until the source is removed or all the atoms have decayed

321
Q

How does radiation damage cells?

A

Radiation will ionse the atoms and molecules within the cells

322
Q

How do lower doses affect cells?

A

Cause minor damage without killing the cells or mutation of cells

323
Q

How do higher doses affect cells?

A

Kill cells completely causing radiation sickness (vomitting, tiredness and hair loss)

324
Q

Compare the risk of radiation outside the body

A

Beta and gamma are the most dangerous with alpha being less dangerous as it can’t penetrate the skin

325
Q

Compare the risk of radiation inside the body

A

Alpha sources are the most dangerous as it’s the most ionising

326
Q

What radiation has the biggest risk with contamination?

A

Alpha

327
Q

What radiation has the biggest risk with irradiation?

A

Beta or gamma

328
Q

How does activity affect the danger of a radiation?

A

The higher the activity, the more dangerous the radiation

329
Q

When choosing a radioactive source for an application, what must you look for?

A

Look to find a balance between a source that has the right level of activity but also the right half life

330
Q

How do fire alarms work?

A

Uses weak source of alpha radiation and two electrodes
Source causes ionisation and a current flows
If there is a fire the smoke will absorb the particles and prevent the current

331
Q

Why can gamma rays be used to steralise?

A

A high dose of gamma rays will kill all microbes

332
Q

Why is irradiation better than boiling?

A

Irradiation doesn’t involve high temperature which would ruin fresh ruit or plastic instruments

333
Q

What would the radioactive source be like for sterilisation?

A

Strong emitter and long half-life

334
Q

What isotopes must be put into a body?

A

Only gamma and beta (never alpha, unless for cancer treatment)

335
Q

What would the radioactive source be like for tracers?

A

Short half-life

336
Q

How else is gamma used?

A

To detect leaks in underground pipes

337
Q

How else is beta radiation used?

A

Thickness control

338
Q

Why must beta radiation be used when measuring thickness control?

A

Because gamma will completely transmit through but also alpha won’t even make it to the object

339
Q

What is PET scanning a technique for?

A

To show tissue or organ function and diagnosis of medical conditions

340
Q

What do you inject into the patient?

A

A substance used by the body with a tracer

341
Q

What occurs once the substance is injected into the patient?

A

The positrons will be emitted which will them meet electrons and annihilate which will then emit gamma rays

342
Q

How can a tumour be found in a PET scan?

A

By triangulation

343
Q

What types of radiation are used to treat tumours internally?

A

Alpha and beta

344
Q

What types of radiation are used to treat tumours externally?

A

Gamma

345
Q

Describe the half-life of internal treatment of tumours

A

Short to limit the amount of exposure time

346
Q

Describe the half-life of external treatment of tumours

A

Long to prevent the need to replace

347
Q

What is nuclear fission?

A

The splitting up of big atomic nuclei

348
Q

What is nuclear fission used to do?

A

Release energy from uranium atoms

349
Q

Describe the process of nuclear fission

A

A slow-moving neutron is fired at a large, unstable nucleus

The nucleus absorbs the nuetron and causes it to split

350
Q

What is created when U-235 splits?

A

Two new lighter elements (daughter nuclei and energy)

351
Q

How is nuclear fission a chain reaction?

A

When the uranium atom splits up, it also spits out two or three neutrons which can hit other uranium nuclei

352
Q

What is the name of the slow-moving neutrons in nuclear fission?

A

Thermal neutrons

353
Q

How are neutrons slowed down?

A

By placing the fuel rods in a moderator

354
Q

How do control rods work?

A

Limit the rate of fission by absorbing excess neutrons

355
Q

What would happen if nuclear fission was left?

A

Large amounts of energy would be released resulting in a runaway reaction which could cause an explosion

356
Q

What is nuclear fusion?

A

The joining of small nuclei

357
Q

True or False? The mass of the heavier nucleus equals the mass of the two seperate, light nuclei?

A

False, because some of the mass is converted to energy

358
Q

What conditions must fusion occur in?

A

High temperature and pressure

359
Q

What temperature is needed for fusion?

A

10,000,000*C

360
Q

Why is such a high temperature needed for nuclear fusion?

A

To overcome the high electrostatic repulsion as the positively charged nuclei have to get very close

361
Q

Why is it really hard to create the right conditions for fusion?

A

No material can withstand that kind of temperature

362
Q

What are the pros of nuclear power?

A 
Pretty safe
Very reliable
Doesn't release bad gases (clean source)
Huge amounts of energy released
Nuclear fuel is cheap and readily available
363
Q

What are the cons of nuclear power?

A

Poor public perception
Hard to dispose of waste products
Risks of leaks
Overall cost is extremely high

Yr 10 Mock (8 decks)

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