4. Energy Resources And Transfers Flashcards
(141 cards)
1
Q
What is energy?
A
The ability to do work
2
Q
What unit is energy measured in?
A
Joules (J)
3
Q
What is the Principle of Conservation of Energy?
A
Energy cannot be created or destroyed only transferred from one store to another
4
Q
What kind of energy do all moving things have?
A
Kinetic energy
5
Q
What increases kinetic energy?
A
Mass and speed of an object
6
Q
What is Gravitational Potential Energy?
A
The ability to fall; higher objects have more
7
Q
Where is Chemical Energy stored?
A
In chemical bonds
8
Q
What is Electrostatic Energy?
A
Energy between charged objects due to electric fields
9
Q
What is Magnetic Energy?
A
Energy between magnetic objects due to magnetic fields
10
Q
Where is Elastic Potential Energy stored?
A
In stretched or compressed springs
11
Q
When is Nuclear Energy released?
A
During radioactive decay fission or fusion
12
Q
What is Absolute Zero?
A
-273 degrees C or 0 Kelvin when gas compresses into a volume
13
Q
How is energy transferred by Heating?
A
Due to temperature difference from hot to cold
14
Q
How is energy transferred by Electric Current?
A
By movement of electrons
15
Q
How is energy transferred by Radiation?
A
By sound and light waves
16
Q
How is energy transferred by Mechanical Work?
A
By forces
17
Q
What energy change occurs when a cup of tea warms up?
A
Thermal energy increases
18
Q
What energy changes occur when a car slows down?
A
Kinetic energy decreases
19
Q
What energy change occurs when a cake is cut in half?
A
Chemical energy decreases
20
Q
What energy changes occur when two attracting magnets are pulled apart?
A
Magnetic potential energy increases
21
Q
What energy change occurs when an elastic band is stretched?
A
Elastic potential energy increases
22
Q
What energy change occurs when a ball is placed high on a shelf?
A
Gravitational potential energy increases
23
Q
What energy change occurs when your hand touches an ice cube?
A
Thermal energy decreases
24
Q
What energy change occurs when a held guitar string is released?
A
Elastic potential energy decreases
25
What happens to gravitational potential and kinetic energy stores when they are increasing?
Gravitational potential and kinetic energy stores are increasing
26
Are all energy transfers useful?
No
27
What are different systems expected to do?
Provide a particular outcome by transferring energy between stores
28
Can an energy transfer between stores be useful or wasteful?
An energy transfer between stores can be useful or wasteful
29
Will all systems have some wasted energy?
All systems will have some wasted energy
30
Describe the energy transfers for a buzzer?
Chemical energy store (in the battery) → Electrical transfer (in the wires) → Electrostatic energy store → Mechanical transfer mechanism (air gets pushed by a force) → Kinetic energy store → Radiation transfer mechanism (as sound) → Into the surroundings (as thermal energy)
31
Describe the energy transfers for a lamp?
Chemically transfer (from the power station) → Electrical transfer mechanism (in the wires) → Thermal energy store (in the filament of the bulb) → Heating transfer mechanism (air gets warmed) → Radiation transfer mechanism (as light) → Some into the surrounding area (as thermal energy) and most into the surrounding area (as light)
32
Describe the energy transfers for a jumping frog toy?
Elastic potential store (in the spring) → Mechanical transfer mechanism (as the spring forces the object to jump upwards) → Kinetic energy store (as the toy moves upwards) → Gravitational potential store (as the toy gains height) → Kinetic energy store (as the toy moves downwards) → Mechanical transfer mechanism (as the object's weight/a force is being moved a distance) → Thermal transfer mechanism to the surroundings on impact
33
Describe the energy transfers for an electrostatic balloon attracting paper?
Electrostatic energy store (on the balloon) → Electrical transfer mechanism (electrostatic force pulls on the paper) → Kinetic energy store (the bits of paper move upwards) → Mechanical transfer mechanism (paper moves upwards against the force of gravity) → Gravitational potential energy store (bits of paper higher up than at the start) → Thermal transfer mechanism to the surroundings on impact
34
Describe the energy transfers for a mass moving up and down on a spring?
Elastic potential store (in the stretched spring) → Mechanical transfer mechanism (as forces pull weight up) → Gravitational potential store (as the mass moves higher up) → Kinetic energy store (as the mass moves up) → Thermal transfer mechanism (air gets warmed) → Kinetic energy store (as the mass moves down) → Gravitational potential store (as the mass moves down) → Elastic potential store (in the compressed spring) → Thermal store increases (from friction in the spring and air resistance) to surroundings
35
Describe the energy transfers for a swinging pendulum?
Gravitational potential store (the mass is displaced upwards) → Mechanical transfer mechanism (momentum carries the object upwards) → Kinetic energy store (as the mass swings to the side) → Gravitational potential store (as the mass moves upwards) → Kinetic energy store (as the mass swings back down) → Thermal store increases (from friction in the string and air resistance) to surroundings
36
Describe the particle arrangement and forces in a solid.
Particles are in fixed positions
Strong forces of attraction
Fixed shape
Fixed volume
37
Describe the particle arrangement and forces in a liquid.
Particles are able to flow
Weaker forces
No fixed shape
Fixed volume
38
Describe the particle arrangement and forces in a gas.
Particles are spread out
Weak forces
No fixed shape
No fixed volume
39
What are the three ways thermal energy can be transferred?
Conduction
Convection
Radiation
40
In which states of matter does conduction mainly occur?
Solids
41
In which states of matter does convection occur?
Liquids and gases
42
In which states of matter does radiation occur?
All states of matter
43
What makes a material a good conductor?
Particles are close together Allows more collisions Solids are good conductors gases are very bad conductors
44
How does conduction occur in metals?
Metals have free delocalized electrons Free electrons are able to move freely around the solid carrying energy from one particle to another
45
How does thermal energy transfer through solids via conduction?
By collisions between particles
46
What is the role of free electrons in conduction in metals?
Free electrons diffuse and collide with other free electrons transferring energy
47
Besides colliding with free electrons what else do free electrons collide with in metals?
Atoms making them vibrate more
48
What property of a material makes it feel colder even at the same temperature?
Higher thermal conductivity
49
Why do materials with high thermal conductivity feel colder?
They transfer heat away from your hand (or body) more quickly
50
What property of a material makes it feel warmer even at the same temperature?
Lower thermal conductivity (insulating properties)
51
Why do materials with low thermal conductivity feel warmer?
They don't transfer heat away from your hand (or body) as quickly
52
In what states of matter does convection occur?
Liquids and gases
53
What is a convection current?
The movement of a fluid due to differences in density caused by temperature variations
54
How does a convection current work?
Warmer less dense fluid rises while cooler denser fluid sinks
55
What happens to air particles near a heater and how does this relate to convection?
The air particles gain thermal energy move faster and expand becoming less dense causing them to rise
56
How does heating water in a saucepan lead to a convection current?
The water particles near the heat source gain thermal energy move faster and expand becoming less dense and rise while cooler denser water sinks creating a circular flow
57
How does cooling water lead to changes in its density and movement?
The water particles lose thermal energy move slower and contract becoming more dense and sink
58
What is the fundamental principle behind how convection currents work in fluids?
Warmer less dense fluid rises while cooler denser fluid sinks creating a circular flow
59
Do all objects with a temperature emit infrared radiation?
Yes all objects emit some infrared radiation
60
What is the relationship between an object's temperature and the infrared radiation it emits?
Hotter objects emit more infrared radiation
61
What type of wave is infrared radiation?
Electromagnetic waves
62
What surface is best for emitting and absorbing heat radiation?
Black surfaces
63
What surface is best at reflecting infrared radiation?
Shiny surfaces
64
Why are houses in hot countries often painted white?
To reflect light and keep the house cooler
65
Why are solar panels often black?
To absorb light to produce energy
66
What is the purpose of insulation?
To reduce unwanted heat transfers to the surroundings
67
What materials are good thermal conductors?
Metals
68
What is an example of a metal object that is a good thermal conductor?
A kettle
69
What is one method to reduce energy transfers from a pan?
Put a lid on it
70
How is heat transferred to its surroundings?
By IR radiation conduction and convection
71
What are three ways energy can be transferred to the surroundings?
By IR radiation conduction and convection
72
Why should thermal energy loss to the surroundings be reduced in certain situations?
To conserve energy and maintain desired temperatures
73
What material is used to insulate walls?
Cavity wall insulation
74
How does cavity wall insulation reduce heat transfer?
Foam has little air pockets to slow down conduction and convection
75
What is the purpose of double glazing in windows?
To reduce heat loss
76
How does double glazing reduce heat loss?
It traps air which is a good insulator and prevents convection currents
77
What is another benefit of double glazing beyond convection?
It also reduces conduction
78
What material are pipes often lined with and why?
A shiny material to reduce conduction and convection
79
What causes the air to move as shown in the diagram of the coastal breeze?
A convection current is formed as warm air rises over the land and cooler air sinks over the sea
80
How is energy transferred to heat all of the potato in a traditional cooker?
Energy is transferred via convection as the hot water heats the potato
81
What is the purpose of the foil in a solar oven?
The foil reflects heat back to the food
82
Why is black a good material to use inside a solar oven?
Black is a good absorber of heat
83
Why does adding clear plastic wrap to a solar oven help it to heat up?
The plastic wrap reduces heat loss
84
What is the role of the trapped air in the solar oven?
The trapped air reduces heat loss by convection
85
What is the purpose of the black paper in the solar oven?
The black paper absorbs radiation and heats up
86
How does a food warmer lamp work?
The lamp emits infrared radiation which is absorbed by the food
87
How is a food warmer lamp similar to a microwave?
Both emit infrared radiation
88
How is a food warmer lamp different from a microwave?
The lamp heats the surface of the food while microwaves penetrate the food and heat water molecules inside
89
What happens when work is done?
Energy is transferred from one store to another
90
How is work measured?
The work done is the amount of energy transferred
91
When is work done?
Work is done whenever a resultant force moves a body in the direction of the force
92
How do forces transfer energy?
Forces transfer energy (do work) mechanically
93
What does the force generally overcome when doing work?
An opposing force
94
What is the formula for calculating work done?
Work done = force x distance
95
What units are used for work done force and distance?
Joules (J) Newtons (N) meters (m)
96
What force is needed to lift an object?
A minimum force that equals the weight of the object
97
What happens when work is done?
Energy is transferred from one store to another
98
What is work done?
The work done is the amount of energy transferred
99
When is work done?
Work is done whenever a resultant force moves a body in the direction of the force
100
How do forces transfer energy?
Forces transfer energy (do work) mechanically
101
What does the force generally overcome when doing work?
An opposing force
102
What is the formula for calculating work done?
Work done = force x distance
103
What units are used for work done force and distance?
Joules (J) Newtons (N) meters (m)
104
What force is needed to lift an object?
A minimum force that equals the weight of the object
105
What does it mean for something to be powerful in a scientific sense?
It can do a lot of work in a short space of time
106
What is power?
The amount of energy transferred each second
107
What is the formula for calculating power?
Power = energy transferred / time taken
108
What is the unit for power?
Watts (W)
109
What does 1 Watt mean?
1 Joule of energy transferred per second
110
What is the relationship between power and temperature in an electric cooker?
The higher the power the hotter the ring
111
Why does a higher power in an electric cooker lead to a hotter ring?
More energy is being transferred by electric current into thermal energy of the ring each second
112
What does a more powerful car transfer more of?
Chemical energy (in the fuel) into kinetic energy
113
What does a more powerful car enable it to do?
Accelerate more rapidly to a high speed
114
What is work done?
Energy transferred
115
What is power?
The energy required to complete 'work done' divided by the time taken
116
What is the formula for kinetic energy?
KE = 1/2 x mass x velocity²
117
What is the unit for kinetic energy, mass and velocity?
Joules (J), kilograms (kg), meters/second (m/s)
118
What is kinetic energy?
Energy stored in an object's movement
119
What is the formula for mass when given kinetic energy and velocity?
m = 2KE / v²
120
What is the formula for velocity when given kinetic energy and mass?
v = square root of 2KE / m
121
How is energy transferred in fossil fuel power generation?
Chemical energy in the fuel is transferred to thermal energy of water by heating. Then transferred by heating to the thermal store of the steam and then transferred to the kinetic energy store of the steam by heating. Then it is transferred mechanically to the kinetic energy store of the turbines and then mechanically to the Kinetic Energy store of the generator and then is transferred electrically to the cables
122
What are the advantages of fossil fuels?
They release a lot of energy and are relatively cheap.
123
What are the disadvantages of fossil fuels?
They are non-renewable
Can enhance the greenhouse effect
124
How is energy transferred in nuclear power generation?
Nuclear energy in uranium is transferred to thermal energy of water by heating. Then to kinetic energy of steam which drives a turbine connected to a generator producing electricity.
125
What are the advantages of nuclear power?
It releases no greenhouse gases and there is lots of uranium left in the world.
126
What are the disadvantages of nuclear power?
It is non-renewable
It can be very dangerous
127
How is energy transferred in wind power generation?
Kinetic energy of moving air is transferred mechanically to kinetic energy of a turbine. Kinetic energy of the generator is transferred away electrically.
128
What are the advantages of wind power?
It is relatively cheap and renewable.
129
What are the disadvantages of wind power?
It requires a lot of space, is quite noisy and not visually appealing
130
How is energy transferred in hydroelectric power generation?
Kinetic energy of moving water is transferred mechanically to kinetic energy of a turbine. Kinetic energy of the generator is transferred away electrically.
131
What are the advantages of hydroelectric power?
It causes no pollution
132
What are the disadvantages of hydroelectric power?
It harms the environment by flooding valleys
133
How is energy transferred in wave power generation?
Kinetic energy of moving water is transferred mechanically to kinetic energy of a turbine. Kinetic energy of the generator is transferred away electrically.
134
What are the advantages of wave power?
It causes no pollution and is renewable.
135
What are the disadvantages of wave power?
Initial costs are high
136
How is energy transferred in geothermal power generation?
Thermal energy of hot rocks is transferred by heating to thermal energy of water. Then
137
What are the advantages of geothermal power?
It does not harm the environment and is renewable.
138
What are the disadvantages of geothermal power?
It is expensive and only possible in certain places.
139
How is energy transferred in solar cell power generation?
Energy from the Sun is transferred by radiation to solar cells
140
What are the advantages of solar cells?
They cause no pollution
141
What are the disadvantages of solar cells?
They are expensive and only work if there is enough sunlight.
