Paper 1 - Is Assessed Flashcards
(138 cards)
1
Q
Define a scalar quantity
A
Has magnitude (size) but no direction
2
Q
Define a vector quantity
A
Has magnitude (size) and direction
3
Q
List 6 vector quantities
A
force, velocity, displacement, weight, acceleration, momentum
4
Q
List 6 scalar quantities
A
speed, distance, mass, energy, temperature, time
5
Q
Explain the difference between speed and velocity
A
- Speed is just how fast you are going with no regard to direction
- Velocity is speed in a given direction
6
Q
State the formula for speed (m/s)
A
distance / time
7
Q
State the formula for distance (m)
A
speed x time
8
Q
Draw a distance/time graph for a journey that travels at: steady speed for 2 secs stops for 5 secs accelerates for 2 secs decelerates for 2 secs
A
Straight line, flat line, steepening curve, levelling curve
Rev. guide page 14
9
Q
How do you calculate the speed from a distance/time graph
A
Speed = gradient = change in y / change in x
10
Q
Velocity/time graph : compare acceleration from gradient
A
gradient = acceleration because acceleration = velocity/time
11
Q
How do you calculate distance from a velocity/time graph
A
distance = area under the graph
12
Q
Draw a velocity/time graph for a journey that travels at: constant acceleration steady speed increasing acceleration steady speed constant deceleration
A
Straight line, flat line, steepening curve, flat, decreasing straight line
13
Q
Why does an object in orbit at constant speed have a changing velocity?
A
It is travelling at the same pace, but changing direction as it moves in a circular motion
14
Q
What is the resultant force acting on an object moving in a circular motion?
A
Force acts towards the centre of a circle keeping it moving = centripetal force
15
Q
What is an objects inertial mass?
A
How difficult it is to change the velocity of an object
16
Q
What is inertia?
A
The tendency for motion to remain unchanged
17
Q
How do you calculate an objects inertial mass?
A
mass = F / a
The ratio of force over acceleration
18
Q
State Newton’s 3rd Law
A
When two objects interact, the forces they exert on each other are equal and opposite
19
Q
Why do skaters of different masses but exerting the same force accelerate at different speeds?
A
Because a = F / m, so whoever has the smaller mass will accelerate faster than the heavier skater
20
Q
Explain how a book is in equilibrium and doesn’t move
A
- the book is pulled down by its weight due to gravity
- the book also pulls up on the earth
- the normal contact force from the table pushes up the book
- the normal contact from the book pushing down on the table
21
Q
What is a normal contact force?
A
An equal and opposite force from the passive
22
Q
What is the action force?
A
The one that instigates the force
23
Q
Define momentum and it’s formula
A
The product of the objects mass and velocity
Mass x velocity
24
Q
Define the conservation of momentum
A
In a closed system:
the total momentum before and event = the same after the event
25
In snooker, with balls of the same size and mass, what happens when they collide?
- one is stationary = zero momentum
- one is moving with a momentum of p=m x v
- balls collide and gives them both momentum
- combined momentum = original
26
Give the typical speeds for wind and sounds, and ferries
Wind = 5-20m/s
Sound in air = 340m/s
Ferries = 15m/s
27
Give the typical speeds for walking, running, cycling
```
Walking = 1.4m/s
Running = 3m/s
Cycling = 5.5m/s
```
28
Give typical speeds for planes, trains, cars in a built up area and cars on a motorway
Plane = 250m/s
Train = 55m/s
Cars in built up area = 13m/s
Cars on motorway = 31m/s
29
What is the value of g on Earth?
10m/s2
| Actually 9.81
30
What must you measure when using light gates to measure speeds of objects?
- measure mass of trolley, unit masses and the hanging hook
| - measure the length of piece of card that will interrupt the light gate beams
31
How do you use light gates to measure the speeds of objects?
- adjust height of ramp until trolley starts to move
- mark a line on the ramp before the first light gate (start)
- attach trolley to the hanging mass by string and let go of trolley
- each light gate will record the time and speed when the trolley passes
32
What are the variables in the experiment with light gates measuring speeds of objects?
```
Independent = mass on hanging hook
Dependent = speed of trolley at light gates
Control = height of ramp, trolley, piece of card
```
33
How can you find an objects speed by using light gates after the experiment has happened?
Acceleration = change in speed / time
Change in speed = speed at second light gate - speed at first light gate
34
What is Newton’s Second Law?
```
F = m x a
Resultant Force (N) = mass (kg) x acceleration (m/s2)
```
35
How can Newton’s 2nd law be used with momentum and time?
Force (N) = change in momentum (kgm/s) / time (s)
36
What is the formula for GPE?
GPE = mgh
37
What is the formula for KE?
KE = 1/2 X mass X speed^2
38
How can energy be transferred?
Mechanically, electrically, by heating, by radiation
39
Define energy when transferred mechanically
A force acting on an object eg pushing
40
Define energy when transferred electrically
A charge doing work eg in a circuit
41
Define energy when transferred by heating
Energy transferred from a hotter object to a colder object
42
Define energy when transferred by radiation
Energy transferred by waves eg energy from the sun
43
What is meant by the conservation of energy?
When energy is converted from one form to another, the total energy before the change has to equal the total of all energies after the change
44
What happens to the energy when a ball rolls upwards?
- ball does work against the gravitational force
| - energy is transferred mechanically from the KE store to the ball’s GPE store
45
What happens to the energy when a moving objects hits an obstacle?
A bat and a ball
- a bat has KE
- some of this is transferred mechanically to the ball’s KE store
- some energy is transferred mechanically to the thermal energy store of the bat and the ball
- the rest is carried away by sound
46
What happens to the energy when an object being is being accelerated by a constant force?
A rock dropped from a cliff
- assuming there’s no air resistance, gravity does work on the rock
- so the rock accelerates towards the ground
- energy is transferred mechanically from the rock’s GPE to its KE
47
What happens to the energy when a vehicle slows down?
- Energy in the KE store of the car is transferred mechanically (due to friction)
- and then by heating to the thermal energy stores of the car and road
48
What happens to the energy when bringing water to a boil in an electric kettle?
- energy is transferred electrically from the mains to the heating element of the kettle
- and then by heating to the thermal energy store of the water
49
What are energy transfers like in a closed system?
There is no net change to the total energy in the system
50
Define the conservation of energy principle
Total energy input = useful energy output + wasted energy
51
What is the formula for efficiency?
```
Useful energy (J)
————————
Total energy (J)
```
52
Why are mechanical processes wasteful of energy?
- frictional forces have to be overcome
- the energy needed to overcome this is transferred to the thermal energy stores of whatever’s doing the work and the surrounding
- this isn’t useful energy and is quickly dissipated
53
What are lubricants, and what do they do?
Can be used to reduce the friction between the objects’ surfaces when they move
Eg. Oils so they can flow easily between objects
54
Why do lubricants help to reduce unwanted energy transfers?
Reduces energy transferred by friction during mechanically transferred energy
55
In a building, what does the lower conductivity of its walls mean?
The slower the rate of energy transfer through them (meaning the building cools slower)
56
How do cavity walls reduce wasted energy transfers?
The air gap reduces the amount of energy transferred by conduction, because air has a very low thermal conductivity
57
What else - in buildings - reduces the rate of energy transfers by heating?
Thicker walls = slower rate of energy transfer
58
What diagrams show efficiency?
Sankey diagrams
- useful energy = top arrow
- wasted energy = bottom arrow
59
What frequency does ultrasound have?
Greater than 20,000Hz
60
What is the frequency of infrasound?
Below 20Hz
61
How do sound waves travel?
Through compressions and rarefraction by causing particles to vibrate
62
What determines a solid’s ability to transmit different frequencies?
Size, shape and structure
63
What are echoes?
Sound waves reflected by hard flat surfaces
64
What happens when sound waves cause your eardrum to vibrate?
The vibrations are passed on to ring bones in your ear called ossicles, through semicircular canals and to the cochlea
65
What does the cochlea do in the ear?
Turns vibrations into electrical signals which get sent to your brain by the auditory nerve
66
How does the speed of sound change is different media?
Travel faster in liquids than gas
| Travel faster in solids than liquids
67
How does the frequency affect the transmission of sound waves?
Frequency doesn’t change from one media to another
68
How does wavelength impact the transmission of sound?
It gets longer when the wave speeds up and shorter when the wave slows down
69
Why doesn’t sound travel in space?
It’s a vacuum so there are no particles to vibrate
70
How can ultrasound be used in foetal scanning?
- Ultrasound waves pass through the body, but some wave is reflected back and detected at a boundary (eg. skin of a foetus)
- the exact timing and distribution of these echoes are processed by a computer to create a video image
71
How is ultrasound used in industrial imaging?
- can be used to find flaws in objects such as pipes
- ultrasound entering a material will usually be reflected by the far side of the material
- so a flaw such as a crack will be reflected sooner
72
How is ultrasound used in sonar in boats?
- called echo sounding
| - finds the distances to the seabed, or to locate objects in deep water
73
What is produced during an earthquake and how do we measure these?
Seismic waves at a range of frequencies, detected by seismometers
74
What do seismologists do?
Work out the time it takes for the waves to reach each seismometer, and which part of Earth don’t receive waves
75
What happens when seismic waves reach a boundary between different layers (of the earths crust)?
Some are absorbed and some will be refracted
76
What happens to seismic waves when they are refracted?
They change speed gradually, resulting in a curved path
77
What happens when the properties of seismic waves change suddenly?
The wave speed changes abruptly and the path has a kink
78
State the two seismic waves
P- waves and S- waves
79
What have seismic waves helped up to discover about the Earth?
The size of the core, and its internal structure
80
What are the 3 properties to P-waves?
- longitudinal
- travel through solids and liquids (so can pass through Earth’s core)
- faster than S-waves
81
What are 3 properties to S-waves?
- transverse
- only travel through solids (can’t travel through Earth’s core)
- slower than P-waves
82
What may different substances do to waves?
| there’s 4 things
Absorb, transmit, reflect, refract
83
Summarise the steady state theory
Matter is always being created
84
Summarise the Big Bang theory
The universe started with an explosion
85
What does the steady state theory mean?
The universe has always and will always exist as it does now
86
What 3 things are included in the steady state theory?
- no beginning nor end to universe
- density is roughly the same
- new matter is being created as Universe expands
87
What is the story to the big bang theory?
- all matter occupied very small space
- tiny space was very hot and dense
- then it exploded
- and started expanding
- giving the universe a finite age
88
What is the current accepted model for the origin of the Universe?
Big Bang Theory
89
According to the Big Bang theory, what is CMB radiation?
Leftover energy from the explosion, proving the universe had a beginning
90
Why is redshift observed for either steady state or Big Bang theory?
In both models objects are moving away from the observer as the Universe expands
91
What is red shift in a car?
Noise sounds lower pitched when it’s travelling away from you because it drops in frequency (the Doppler effect)
92
What do different elements absorb?
Different frequencies (wavelengths) of light
93
What does each element produce when absorbing frequencies of light?
A specific pattern of dark lines at the frequencies it absorbs on the visible part of the EM spectrum
94
What is wrong with the frequencies of light from distant galaxies we look at?
Light from distant galaxies has the same pattern but at lower frequencies
95
What is red shift?
An observed increase in the wavelength of light coming from the galaxies and the patterns have been shifted towards the red end of the spectrum
96
What does redshift measurements suggest about galaxies?
That all distant galaxies are moving away from us very quickly
97
Do more distant galaxies have greater or lesser red shifts?
Greater red shifts than nearer ones showing a bigger observed increase in wavelength
98
What radiation have scientists detected coming from all parts of the Universe?
Waves in the microwave part of the EM spectrum called CMB Radiation
99
What does CMB radiation stand for?
Cosmic Microwave Background
100
Angle of incidence =
Angle of reflection
101
Define the angle of incidence
The angle between the incoming wave and the notmal
102
Define the angle of reflection
The angle between the reflected wave and the normal
103
What is the normal?
An imaginary line that’s perpendicular to the surface at the point of incidence
104
What is total internal reflection?
When the angle of incidence is larger than the critical angle for this particular boundary between materials
105
When can TIR actually happen?
This can only happen when the wave travels through a dense material like glass of water toward a less dense substance like air
106
When light is reflected by something rough, how does the surface look?
Matt
107
When light is reflected by something smooth, how does the surface look?
Clear like a mirror
108
What is white light made of?
A mixture of all the different colours of light which have different wavelengths
109
What are opaque objects?
Objects that do not transmit light - they absorb some wavelength and reflect others
110
How much light does white reflect?
Reflects all wavelengths equally
111
How much light does black reflect?
Absorb all wavelengths
112
What do transparent and translucent mean?
```
Transparent = see-through
Translucent = partially see-through
```
113
How do colour filters work?
Filter out different wavelengths of light so that only certain colours (wavelengths) are transmitted and the rest are absorbed
114
If you look at a blue object through a blue filter, what colour does the object appear?
Blue
- blue light is reflected from the object
- blue is transmitted by the filter slso
115
If you look at a red object through a blue filter, what colour does the object appear?
Black
| - all the light reflected by the object will be absorbed by the filter
116
What relates to the power of the lens?
Shape and focal length
117
Draw a ray diagram for converging lens
Arrows bend inwards in lens and then you beards when the leave the normal
118
Draw a ray diagram for a diverging lens
Rays bend outwards in the lens and then outwards outside
119
What is converging?
Convex
120
What is diverging?
Concave
121
What is a real image?
Formed when the light rays actually come together to form the image
122
What is a virtual image?
When the light rays from the object appear to be coming from a completely different place to where they’re actually coming from
123
How can a real image be captured on a screen?
The light rays actually meet at the place where the image seems to be eg. On the eye’s retina
124
How come a virtual image can’t be captured on a screen?
Light rays don’t actually come together at the point where the image seems to be eg. Magnifying glasses create virtual images
125
converging lens = what power?
| diverging lens = what power?
```
Converging = power is positive
Diverging = power is negative
```
126
The curvature of a lens affects...
It’s power
127
Define background radiation
Low level radiation around us all the time
128
Give examples of background radiation
Foods, building materials, rocks, cosmic rays, nuclear explosions
129
Define irradiation
Being exposed to radiayion
130
Ways to reduce irradiation
lead-lined boxes, photographic film badges to record exposure, gloves, long-handled tongz
131
what is an alpha particle?
a helium nucleus, doesn’t penetrate very far, strongly ionising, absorbed by thin paper
132
What is a beta particle
Electrons or positrons, moderately ionising, absorbed by sheet of aluminium
133
What is a gamma particle
EM waves with a short wavelength, weakly ionising, penetrate very far, absorbed by thick sheets of lead or concrete
134
Alpha decay nuclear equation
4
| 2
135
Beta minus decay nuclear equation
0
| -1
136
Beta plus / positron decay nuclear equation
0
| 1
137
Neutron emission nuclear equation
1
| 0
138
Do gamma rays have a nuclear equation
No
Mass and atomic numbers stay the same after a gamma ray has been emitted
