1
Q
Equation for kinetic energy?
A
Kinetic energy (J) = 1/2 x mass (KG) x velocity^2
2
Q
Equation for gravitational potential energy?
A
GPE = mass x gravitational field strength x height
3
Q
Equation to find power?
A
Power = work done/time taken = energy transferred/time taken
4
Q
Two equations for finding efficiency?
A
Efficiency = useful energy output/total energy input
OR
efficiency = useful power output/total power input
(to find percentage, multiply answer by x100)
5
Q
Equation for density?
A
Density = mass/volume
6
Q
Equation for wave speed?
A
Wave speed = frequency x wavelength
7
Q
Equation for weight?
A
Weight = mass x gravitational field strength
8
Q
Equation for work done?
A
Work done = force x distance
(moved along the line of action of the force)
9
Q
Equation for force?
A
Force = spring constant x extension
10
Q
Equation for distance travelled?
A
Distance travelled = speed x time
11
Q
Equation for acceleration?
A
Acceleration = change in velocity/time taken
= final velocity - initial velocity/time taken
12
Q
Equation for the resultant force?
A
Resultant force = mass x acceleration
13
Q
Equation for momentum?
A
Momentum = mass x velocity
14
Q
What is the law of conservation of energy?
A
Input energy = output energy,
Energy cannot be created or destroyed, only transferred from one type to another.
15
Q
Name as many of the 9 energy stores and transfers that you can and give an example or two for each
A
-gravitational potential (a book on a shelf/a bungee jumper)
-electrical (anything that uses electricity)
-kinetic (anything that is moving)
-chemical (food, batteries, burning things)
-thermal (hot water, hot radiator)
-sound (talking, TV, radio)
-nuclear (nuclear bombs, power stations)
-light (light bulbs, a bunsen flame)
-elastic potential (a wind-up toy, a rubber band)
16
Q
what is useful and wasted energy?
A
useful energy is what we want out of the device, wasted energy is everything else that is made. e.g. heat is almost always wasted in any energy transfer
17
Q
what is a Sankey diagram?
A
a Sankey diagram shows us how the energy of a device is transferred, it’s sometimes called an Energy Conversion Diagram. Input is on the left, outputs are on the right. Total input=Total output.
18
Q
Is Sankeys Diagram drawn to scale or not?
A
it is drawn to scale, each millimetre represents a certain number of Joules
19
Q
What is efficiency in relation to energy a measure of?
A
Efficiency is a measure of how good a device is at changing energy from one form to another. All devices waste energy, so the efficiency of a device is never 100%. The more efficient a device is the less energy is wasted.
20
Q
What is energy measured in?
A
Joules (J)
21
Q
Practice question: What are the main energy transfers in a radio?
A
electrical —-> sound energy(useful) and thermal energy (wasted)
22
Q
Practice question: A woman pushes a car with a force of 400N for a distance of 15m. How much work has she done?
A
400N x 15m = 6000J
23
Q
Practice question: A lorry has a mass of 20,000 kg. If its kinetic energy is 2.25MJ, at what velocity is it travelling?
A
KE = 1/2 x mass x velocity^2
(2.25MJ x 1000000 = 2250000J)
2250000 = 1/2 x 20000 x velocity^2
2250000 = 10000 x velocity ^2
2250000/10000 = velocity^2
225= velocity^2
15 = velocity
15 m/s
24
Q
what is gravitational potential energy?
A
the energy an object has due to its position above Earth, energy due to its height
25
what are some energy carriers?
-mechanical (when a force moves through a distance)
-electrical (when a charge moves through a potential difference)
-by heating (because of a temperature difference)
-by radiation (e.g. light, microwaves, sound)
26
what is work defined as?
the energy transferred by a force
27
what is power defined as?
the energy transformed or transferred per second
28
what is spring constant?
force per unit extension of a spring
29
what is Hooke’s law?
the extension of a spring is directly proportional to the force applied, as long as its limit of proportionality is not exceeded.
30
what is input energy?
energy supplied to a device
31
what is dissipated energy?
the energy that is not usually transferred and stored in less useful ways
32
what is black body radiation?
the radiation emitted by a perfect black body (a body that absorbs all the radiation that hits it)
33
what is infrared radiation?
electromagnetic waves between visible light and microwaves in the electromagnetic spectrum
34
what is specific heat capacity?
energy needed to raise the temperature of 1kg of a substance by 1°C
35
what is thermal conductivity?
property of a material that determines the energy transfer through it by conduction
36
are materials that contain trapped air good thermal conductors?
no
37
is energy transferred faster through thin walls than through thick walls?
yes
38
write instructions for specific heat capacity required practicals:
1. Check the mass of the aluminium block -it will be written on the block.
2. Place the block on an insulating mat.
3. With the power supply switched off, set up the apparatus as shown in the diagram.
4. Check with your teacher that the joulemeter (or Ammeter and Voltmeter combination) is correctly connected to the heater and the power supply.
5. Place the thermometer in the aluminium block and measure the temperature of the block. Record this as the ‘starting temperature’ of the block.
6. Switch the power supply on.
7. Watch the reading on the thermometer, and when it reaches about 15°C above the starting temperature, switch off the power supply.
8. Record the joulemeter (or Ammeter and Voltmeter combination) reading and the thermometer reading.
9. The thermometer reading might continue to increase for up to a few minutes after the heater has been switched off. Measure and record the highest reading of the thermometer after the heater was switched off.
39
what is biofuel?
any fuel taken from living or recently living materials, such as animal waste
40
what is carbon-neutral?
a biofuel from a living organism that takes in as much carbon dioxide from the atmosphere as is released when the fuel is burned
41
what is geothermal energy?
energy released by radioactive substances deep within the earth
42
what is the national grid?
the network of cables and transformers used to transfer electricity from power stations to consumers (i.e. homes, shops, offices, factories etc)
43
what is nuclear fuel?
substance used in nuclear reactors that releases energy due to nuclear fission
44
what is a nucleus?
tiny positively charged object composed of protons and neutrons at the centre of every atom
45
what is a reactor core?
the thick steel vessel used to contain fuel rods, control rods and the moderator in a nuclear fission reactor
46
what is renewable energy?
energy from natural sources that is always being replenished so it never runs out
47
what is the boiling point?
temperature at which a pure substance boils or condenses
48
define density
mass per unit volume of a substance
49
define freezing point
the temperature at which a pure substance freezes
50
define internal energy
the energy of the particles of a substance due to their individual motion and positions
51
define latent heat
the energy transferred to or from a substance when it changes its state
52
define melting point
temperature at which a pure substance melts or freezes (solidifies)
53
define physical change
a change in which no new substances are produced
54
define pressure
force per unit cross-sectional area for a force acting on a surface at right angles to the surface. The unit of pressure is the pascal (Pa) or newton per square metre (N/m^2)
55
define specific latent heat of fusion Lf
energy needed to melt 1kg of a substance with no change of temperature
56
define specific latent hear of vaporisation Lv
energy needed to boil away 1kg of a substance with no change of temperature
57
Define displacement
Distance in a given direction
58
Define driving force
Force of a vehicle that makes it move (sometimes referred to as motive force)
59
Define forces
A force (in newtons, N) can change the motion of an object
60
Define a free-body force diagram
A diagram that shows the forces acting on an object without any other objects or forces shown
61
Define friction
The force opposing the relative motion of two solid surfaces in contact
62
Define magnitude
The size or amount of a physical quantity
63
What is Newton's first law of motion?
If the resultant force on an object is zero, the object stays at rest if it is stationary, or it keeps moving with the same speed in the same direction
64
What is Newton's third law of motion?
When two objects interact with each other, they exert equal and opposite forces on each other
65
Define a parallelogram of forces
A geometrical method used to find the resultant of two forces that do not act along the same line
66
Define resultant force?
A single force that has the same effect as all the forces acting on the object
67
Define a scalar quantity
A physical quantity, such as mass or energy, that has magnitude only (unlike a vector which has magnitude and direction)
68
Define a vector quantity
a vector is a physical quantity, such as displacement or velocity, that has a magnitude and a direction (unlike a scalar which has magnitude only)
69
Define acceleration
Change of velocity per second (in metres per second, m/s^2
70
Define deceleration
Change of velocity per second when an object slows down
71
Define displacement
Distance in a given direction
72
Define the gradient (of a straight line graph)
Change of the quantity plotted on the y-axis divided by the change of the quantity plotted on the x-axis
73
Define the tangent
A straight line drawn to touch a point on a curve so it has the same gradient as the curve at that point
74
Define velocity
Speed in a given direction (in metres/second, m/s)
75
Define braking distance
The distance travelled by a vehicle during the time it rakes for its brakes to act
76
Define the conservation of momentum
In a closed system, the total momentum before an event is equal to the total momentum after the event. Momentum is conserved in any collision or explosion, provided no external forces act on the objects that collide or explode
77
Define directly proportional
Two or more factors that increase at the same rate. A graph will show this if the line of best fit is straight through the origin
78
Define elastic
A material is elastic if it is able to regain its shape after it has been squashed or stretched
79
Define extension
The increase in length of a spring (or a strip of material) from it's original length
80
Define gravitational field strength, g
The force of gravity on an object of mass 1kg (in newtons per kilogram, N/kg). It is also the acceleration of free fall
81
Define inertia
The tendency of an object to stay at rest or to continue in uniform motion
82
Define the limit of proportionality
The limit for Hooke's law applied to the extension of a stretched spring
83
Define mass
The quantity of matter in an object - a measure of the difficulty of changing the motion of an object (in kilograms, kg)
84
Define momentum
This equals mass (in kg) x velocity (in m/s)
85
What is Newton's second law of motion?
The acceleration of an object is proportional to the resultant force on an object, and inversely proportional to the mass of the object
86
Define stopping distance
The distance travelled by the vehicle in the time it takes for the driver to think and brake
87
Define terminal velocity
The velocity reached by an object when the drag force on it is equal and opposite to the force making it move
88
Define thinking distance
The distance travelled by the vehicle in the time it takes the driver to react
89
Define weight
The force of gravity on an object (in newtons, N)
90
Define amplitude
The height of a wave crest pr trough of a transverse wave from the rest position. For oscillating motion, the amplitude is the maximum distance moved by an oscillating object from its equilibrium position
91
Define compression
Squeezing together
92
Define echo
Reflection of sound that can be heard
93
Define electromagnetic waves
Electric and magnetic disturbances that transfer energy from one place to another
94
Define frequency
The number of wave crests passing a fixed point every second
95
Define longitudinal waves
Waves in which the vibrations are parallel to the direction of energy transfer
96
Define mechanical waves
Vibration that travels through a substance
97
Define oscillate
Move to and fro about a certain position along a line
98
Define rarefaction
Stretched apart
99
Define reflection
The change of direction of a light ray or wave at a boundary when the ray or wave stays in the incident medium
100
Define refraction
The change of direction of a light ray when it passes across a boundary between two transparent substances (including air)
101
Define speed
The speed of an object (metres per second) = distance moved by the object (metres) / time taken to move the distance travelled (seconds)
102
Define transmission/transmitted
A wave passing through a substance
103
Define a transverse wave
A wave where the vibration is perpendicular to the direction of energy transfer
104
Define vibrate
Oscillate (move to and fro) rapidly about a certain position
105
Define wavelength
The distance from one wave crest to the next
106
Define carrier waves
Waves used to carry any type of signal
107
Define charge-coupled device (CCD)
An electronic device that creates an electronic signal from an optical image formed on the CCD's array of pixels
108
Define 'contrast medium'
An X-ray absorbing substance used to fill a body organ so the organ can be seen on a radiograph
109
Define electromagnetic spectrum
The continuous spectrum of electromagnetic waves
110
Define microwaves
Electromagnetic waves between infrared radiation and radio waves in the electromagnetic spectrum
111
Define optical fibre
Thin glass fibre used to transmit light signals
112
Define radiation dose
Amount of ionising radiation a person receives
113
Define radio waves
Electromagnetic waves of wavelengths greater than 0.10m
114
Define ultraviolet radiation (UV)
Electromagnetic waves between visible light and x-rays in the electro-magnetic spectrum
115
Define wave speed
The distance travelled per second by a wave crest or trough
116
Define white light
Light that includes all the colours of the spectrum
117
Define X-rays
Electromagnetic waves smaller in wavelength than ultraviolet radiation and produced by X-ray tubes
118
Write the method for the Thermal Radiation required practical
1. Set up the four identical flasks painted black, grey, white and silver.
2. Fill the flasks with hot water, ensuring the measurements start from the same initial temperature
3. Note the starting temperature, then measure the temperatures at regular intervals e.g. every 30 seconds for 10 minutes.
119
How do all warm objects emit thermal radiation?
In the form of infrared waves
120
Write the method for the Hooke's Law required practical
1. Attach the spring to the clamp stand by hanging it off a clamp, and allow the spring to hang freely over the side of the bench.
2. Use the G-clamp to fasten the clamp stand to the bench.
3. Use the other two clamps to hold the ruler vertically, close to but not touching the spring. You will use this to measure the length of the spring.
4. Measure the length of the spring with no force acting on it.
5. Hang the mass holder from the spring. Check the mass of the holder, and measure the new length of the spring. Record the length of the spring and the mass suspended from it.
6. Add a 50 g (0.5 N) mass and measure the length of the spring.
7. Repeat step 6 until a total of 250 g (including the mass holder) is hanging from the spring. Each time, record the length of the spring and the total mass suspended from the spring.
8. Remove 50 g.
9. Measure the length of the spring.
10. Repeat steps 8 and 9 until there is no mass hanging from the spring.
11. Record all your results in a table.
121
Write the method for Measuring the Density of Regularly Shaped Objects Required Practical:
1. Place the object on a digital balance and note down its mass
2. Use either the ruler, Vernier calipers or micrometer to measure the object’s dimensions (width, height, length, radius) – the apparatus will depend on the size of the object
3. Repeat these measurements and take an average of
these readings.
1. Calculate the volume of the object depending on
whether it is a cube, sphere, cylinder (or other regular
shape)
2. Using the mass and volume, the density of each can be calculated using the equation: p = m/v
122
Write the method for Measuring the Density of Irregularly Shaped Objects Required Practical:
1. Place the object on a digital balance and note down
its mass.
2. Fill the eureka can with water up to a point just below the spout
3. Place an empty measuring cylinder below its spout
4. Carefully lower the object into the eureka can
5. Measure the volume of the displaced water in the
measuring cylinder
6. Repeat these measurements and take an average
7. The volume of the water displaced is equal to the
volume of the object
8. Once the mass and volume of the shape are known,
the density can be calculated using: p = m/v
123
Define the term 'thermal conductivity'
Thermal conductivity is the ability of a material to allow the flow of heat from its warmer surface through the material to its colder surface.
124
Give three examples of materials that have a high thermal conductivity
Diamond, silver, copper
125
Give three examples of materials that have a low thermal conductivity
Oil, alcohol, acrylic glass
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