Physics Flashcards
(125 cards)
1
Q
Speed=
A
Distance/Time-m/s-v=d/t
2
Q
Gradient of a line=
A
y step/x step=speed on a distance-time graph
3
Q
On a distance-time graph what does a steep and shallow curve mean?
A
Steep-High Speed
Shallow-Low Speed
4
Q
On a distance-time graph what does a constant gradient (not horizontal though) mean, and what does a horizontal line mean?
A
Constant gradient=constant speed
Horizontal Line=Speed is 0
5
Q
What type of quantity is velocity and acceleration?
A
It is a vector quantity, it is equal to speed in a particular direction and has a size
6
Q
Acceleration=
A
Change in Velocity/Time-m/s/s-a=triangle v/t
7
Q
In Speed-Time graphs what is the area under the graph?
A
Distance Travelled
8
Q
In Speed-Time graphs what is the gradient of the line equal to?
A
Acceleration
9
Q
On a Speed-Time graph what does a flat/horizontal line mean?
A
Constant Speed
10
Q
On a Speed-Time graph what does a straight/constant line mean?
A
Constant Acceleration
11
Q
Weight=
A
mass x gravitational field strength-N/kg-w=mg
12
Q
On Earth what is gravitational field strength?
A
10N/kg
13
Q
Mass is measured in
A
kg
14
Q
Density=
A
Mass(g)/Volume(cm3)-g/cm3-odd p=m/v
15
Q
Moment of a force about a pivot=
A
Force x perpendicular distance from the pivot
16
Q
What is Hooke’s Law?
A
F=kx
Applied Force=Force Constant for Object Under Test x extension of spring
Extension should be directly proportional to the applied force provided that the elastic limit is not exceeded
17
Q
Force=
there are 5 answers
A
Mass x Acceleration Moment of a Force/Perpendicular Distance to Pivot Spring Constant x Extension Work Done/Distance Area x Pressure
18
Q
Kinetic Energy=
A
1/2mass x velocity squared
19
Q
Resultant force is the
A
net or overall force when size and direction of all the forces acting are taken into account
20
Q
What is centripetal force?
A
The force which causes an object to move in a circle, usually acting at right angles to the direction the object is travelling at (like a swingball)
It acts towards the centre of a circle
21
Q
The larger the mass (when it comes to centripetal force)
A
the larger the inertia (resists change in motion)
22
Q
How do you increase centripetal force?
A
The mass of object increases
The speed of object increases
Radius of circle decreases
23
Q
What is the significance of the limit of proportionality of an extension/load graph?
A
The point where the spring won’t go back into it’s original shape, so F doesn’t=kx anymore
24
Q
What is meant by the centre of mass?
A
Where all the mass of an object can be considered to be concentrated
25
What circumstances are needed for an object to topple over?
The line of action of its weight is outside its base
26
Describe Brownian motion
The random movement of small particles in a gas or a liquid. The particles are constantly being hit rapidly by other moving particles
27
Pressure(Pa)=
Force/Area
Depth x density x gravitational field strength
Also to note Boyles Law= pV = constant
so p1V1=p2V2 Pressure x volume = constant
28
Describe a Mercury Barometer
A barometer half filled with mercury, and a vacuum above that, The bottom part is exposed to the air, and its pressure, so when it increases the volume of the vacuum drops, and the mercury rises. Measures atmospheric pressure
29
How do you show in an experiment that pressure increases with depth in liquids?
Make holes in a water bottle and fill it with water. The water spewing out of the top holes will not travel so far and so fast, but the pressured holes below will, for the weight of water above them will push down
30
How does a manometer work?
Measures pressure of a gas. U-Shaped glass piece with gas attached at one end and free to air at other. Half filled with liquid. The liquid on both sides will go up and down from being equal to each other when gas is attached
31
What is the equation for a manometer?
Atmospheric Pressure + Density of liquid x gravitational field strength x difference in height of 2 liquid surfaces
Pressure = atmospheric pressure +pgh
32
What is the difference between scalar and vector quantities?
Scalar-Size only
| Vector-Size and Direction
33
```
Name the heat transformations in a
Light Bulb
Waterfall
Bow and Arrow
Battery/Cell
```
Light Bulb: Electric to heat and light
Waterfall: Gravitational potential to kinetic
Bow and Arrow: Strain to kinetic
Cell: Chemical to electrical
34
What are the three things can happen to energy?
Be transferred, be transformed or be stored
35
Describe gravitational potential energy and kinetic energy
GPE: The energy gained as an object is lifted away from the earth
KE: An energy an object has due to movement
36
Describe strain and chemical energy
Strain: The energy stored when an object changes shape
Chemical: Stored energy that can be released in chemical reactions
37
Describe internal energy, sound energy and electrical energy
Internal: The total kinetic and potential energies of all the particles in an object
Sound: Energy carried by a sound wave
Electrical: Energy carried by an electrical current
38
Describe thermal (heat) energy
The energy released when the temperature of a hot object decreases due to a decrease in its internal energy
39
Power (W)=
| Electrical Power=
Energy/time
| Current x Voltage
40
Angle of incidence (in reflection) is equal to...
...the angle of reflection
41
When light goes from a less dense material to a denser one, or slows down, it bends...
...towards the normal
42
When light goes from a denser material to a less dense one, or speeds up, it bends...
...away from the normal
43
Refractive Index, n=
Speed of Light in a Vacuum/Speed of Light in the Material
or
sin i / sin r
44
When does refraction turn to total internal reflection?
When the angle of incidence = the critical angle
45
When total internal reflection is taking place what is the angle of reflection?
The angle of incidence
46
In refraction what is the angle of refraction (equation)?
Sin(Angle of Incidence)/Refractive Index
| Then that number Sin-1(
47
Which colours travel the fastest and slowest in glass?
Fastest-Red
| Slowest-Violet
48
What is it called when light spreads out into the colours of the spectrum?
Dispersion
49
From lowest energy (longest wave length) to highest energy (shortest wave length) name the 7 things on the electromagnetic spectrum
```
Radio
Microwave
Infra-Red
Visible Light
Ultra-Violet
X-Radiation
Gamma
```
50
What type of waves are longitudinal and which ones are transverse?
Longitudinal-Sound Waves
| Transverse-Light Waves
51
What are sound waves made up of?
Compressions and Rarefactions
52
Higher frequency of a sound wave means a higher...
...pitch produced
53
The greater the amplitude of a sound wave the higher...
the volume is, the sound is louder
54
Describe an experiment to find the speed of sound in air
Place 2 microphones apart and measure the distance between them. Then hit an object with a hammer, such as a metal plate. The difference in time between the sound wave reaching the 2 microphones is the time
Use equation v=d/t
55
What is Boyles Law?
pV=constant or for a fixed mass of gas at room temperature the volume is inversely proportional to the applied pressure
56
Describe Evaporation
The transformation from a liquid to a gas at a temperature below the boiling point of the liquid. Some particles have more kinetic energy than others and some may be moving fast enough to overcome the forces of attraction between them and other particles. These particles escape from the surface of the liquid
57
How do you increase the rate of evaporation?
Increase temperature of liquid
Increase surface area
Increase air flow over surface of liquid
58
How does a bimetallic strip work in a thermostat?
As the brass expands more than the invar does when it gets hot, the strip bends when heated. When the temperature rises the strip bends away from the circuit contact so the heater turns off
59
What is 0 Kelvin in Degrees Celsius?
-273 Degrees Celsius
60
What is a Thermistor?
An electrical component whose resistance decreases with temperature increase, it allows more current to flow when the temperature increases. The current reading is then converted to a temperature reading on a digital meter
61
What is a Thermocouple?
2 different types of metal are joined together to form 2 junctions. When there is a temperature difference between the metals there is also a potential difference created, so when the 2 junctions are placed in different temperatures the potential difference can be converted into a temperature reading
62
What is latent heat of fusion?
The energy which must be put in to melt a solid or is given out when a liquid solidifies at its freezing point
63
What is the latent heat of vaporisation?
The energy which must be put into a liquid at its boiling point or is given out when a gas at its boiling point condenses
64
Describe an experiment to find the latent heat of fusion of ice
Fill a funnel with ice with a beaker (measure weight of this) below it and place a heater in it. After 10 minutes remove the beaker and switch off the heater and subtract original mass of beaker from the new mass to find mass of ice melted. Use equation change in mass x specific latent heat=energy transferred
65
Energy Transferred=
mass x specific latent capacity x temperature change
or
mass x specific latent heat
66
Describe an experiment to find the specific latent heat of vaporisation of water
Partly fill a beaker with boiling water and place a 50W electrical heater in the water. Wait for the water to boil, when it does start the stop watch when it does and wait for the mass of the beaker to drop by 0.1kg`. Use equation change in mass x specific latent heat=energy transferred
67
What is the effect on an alpha particle of it passing through an electric field?
Attracted to negative terminal as it is positive
Use Fleming's Left Hand Rule to figure out direction of movement with motion of particles as current. They are deflected at right angles to the field and their original direction
68
What is the effect on a beta particle of it passing through an electric field?
Attracted to positive terminal as negative
Deflected in opposite direction to the alpha particles
They are deflected more as they have a lower mass
69
What is the effect on a gamma particle of it passing through an electric field?
Not deflected at all
70
How effective is the penetrating effect of an alpha particle?
Not very penetrating, getting absorbed by a few cm of air or a few sheets of paper
71
How effective is the penetrating effect of a beta particle?
More penetrating than alpha, absorbed by a few mm of aluminium
72
How effective is the penetrating effect of a gamma particle?
Very penetrating, not completely absorbed by lead or thick concrete
73
What do you call the molecules on either side of the decay equation?
Parent Nucleus turns to Daughter Nucleus
74
When an element decays via alpha decay what happens to its proton and nucleon number?
Its proton number decreases by 2 and its nucleon number by 4 as it expels a positive helium nucleus
75
When an element decays via beta decay what happens to its proton and nucleon number?
Nucleon number stays the same as the neutron that breaks down into a proton and an electron that makes up for the original loss on the nucleon number. The proton number increases by 1 as it creates a new proton . An electron with the charge 0 -1 is expelled
76
When an element decays via gamma decay what happens to its proton and nucleon number?
It does not change, the gamma ray takes away some of the excess energy of the nucleus after it emits an alpha or beta particle
77
Name some uses of radioisotopes
```
Medical Tracers
Carbon Dating
Monitoring Thickness (in manufacturing of paper)
Detecting Leaks
Medical Therapy (radiotherapy)
```
78
What is a nuclide?
An atom which is specified by its proton and nucleon number (like a normal element with 2 number)
79
What are isotopes?
Different versions of the same element that have the same number of protons but different number of neutrons
80
What are dynamos and alternators?
Current Generators
81
What is the advantage of high-voltage transmission?
There are less line losses as the current is lower so there are less electrons in the wire so there are less collisions and heat energy losses in the wire
82
Why is it that transformers have laminated soft iron cores?
So that there is a reduction in Eddy currents which are caused when electrons have the ability to spin around in a circle fully. By making the cores thinner the electrons can not do this energy wasting manoeuver
83
What is the solenoid rule?
When your right hand is against a solenoid and your thumb is pointing towards the north pole, your fingers represent the direction of current
84
What is a transformer?
A electrical component that either steps up or steps down a voltage
85
How does a transformer work?
An emf is produced by the wire cutting the magnetic field and relative motion (the alternating current). Due to this the voltage between the primary coil and secondary coil (depending on the number of turns) is either increased or decreased
86
What does a motor use and what does a generator use?
DC motor-Split Ring Commutator
| AC Generator-Slip Rings and Brushes
87
What is Lenz's Law?
A magnet moving through a metal tube moves slowly as it induces a current in the tube turning KE to electrical energy
88
Describe electromagnetic induction
An emf is produced by a magnetic field cutting a wire with relative motion. This can be done by pushing a magnet through a solenoid and is what happens in a generator
89
What does a full wave rectifier do?
Turn AC into DC
90
How can electromagnetic induction be increased?
Faster relative motion-Higher number of coils-Stronger magnet
91
What features of a Hooke's law graph makes it a Hooke's law graph?
The line is straight and is through the origin
92
Work done=
Energy and force x distance, so power = force x distance/time
93
Difference between force and moments when describing them
When talking about force use upward or downwards or the like, and when talking about moments use (anti)clockwise
94
Why is it not necessary to know the weight of the beam a see saw has when figuring out moments?
The weight has no moment
95
What type of conductor is air?
A poor one
96
If a metal strip is painted different colours on either side, why does it cool at the same rate?
The metal may be a good conduct so the heat will evenly conduct through the metal
97
Why are many waves described as transverse?
Motion of the line (rope in some circumstances) is at right angles to the direction of the wave
98
What happens in an iron core when an alternating current is in a coil of one side of the transformer?
Magnetic field in core is alternating
99
When it says define in a question, what do you do?
Put the equation in words?
100
When it says describe an experiment, how do you get a cheeky mark?
Check device is on zero
101
Is there such a thing is wind resistance?
No, there is air resistance or drag
102
What is the air resistance of a parachuter falling through the air with his parachute open?
W=mg
103
How does sweating help cool the body down?
When sweat evaporates off the body it takes energy with it. The sweat molecules are cooler so the body warms the sweat, using energy and taking internal energy away from the body
104
What is the range of frequencies that can be heard by a healthy human ear?
20Hz-20,000Hz
105
State in terms of molecules what is meant by a compression and rarefaction
Compression-molecules are being pushed together and the pressure is raised, with rarefaction is the opposite
106
Why do forces on a d.c. Motor cause spinning?
They have moments in the same direction, and opposite forces
107
Why are split-ring commutators used?
So a full rotation can be achieved by not reversing the current in the loop, so coil can turn more than a half revolution
108
What does an alpha particle consist of?
2 protons and 2 neutrons, a helium nucleus
109
What is meant by the ionisation of a gas molecules?
The electrons are removed from the molecule
110
Why might a sled on a tracks acceleration be constant?
Mass of sled decreased as fuel is burnt
111
What is a good way to describe air molecules motion and when comparing them?
Sudden change in movement, random motion. If comparing then use lightness=faster motion, and describe both molecules random motion
112
How do you describe what happens to pressure in terms of molecules when temperature is increased in a constant volume?
Pressure increases as gas molecules collide more frequently and harder with the walls
113
How does one draw diffraction?
With the waves the same distance apart as before, and with some form of an arc
114
If an image is virtual how where can it be seen from?
On the other side of the lens, between the 2 rays
115
When a diode is working, does it worry about conventional current or electron moving current?
Conventional current
116
How do you achieve demagnetisation with a solenoid and a bar magnet?
A.C. Current in the solenoid with the bar magnet going through the solenoid slowly
117
Light waves are? Radio waves are?
Both are transverse
118
How do measure the critical angle?
You take the angle from 90 degrees on the protractor to the line
119
What is meant by the term monochromatic?
Single wavelength
120
Describe your average virtual image?
Virtual, larger, upright
121
When is a virtual lens used?
Binoculars
122
What are some precautions that must be taken before doing a pin and plane mirror experiment
Pins straight up, mirror is straight
123
What happens to the temperature of a substance thermal energy removed causes a change in state?
No change
124
If ice is added to a cup of water, what is the thermal energy lost by the water equal to?
The thermal energy gained by the ice
125
Why does the mercury level rise in a thermometer when heat is applied?
Heat flows through glass and to mercury causing liquid to expand
