Nat 5 Physics Flashcards
(113 cards)
1
Q
Whats the difference between vectors and scalars?
A
Vectors have magnitude and direction
Scalars only have magnitude
2
Q
Name some vectors.
A
Force
Acceleration
Displacement
Velocity
Weight
3
Q
Name some scalars.
A
Distance
Length
Speed
Energy
Volume
Mass
4
Q
What is the difference between speed and velocity?
A
Speed is a measure of the distance an abject moves in a given time. (scalar)
Velocity is a measure of speed in a given direction. (vector)
5
Q
What is the most important rule when writing the magnitude of vectors?
A
You also give the direction
6
Q
What is d=vt ?
A
distance = speed x time
7
Q
What is s = vt ?
A
displacement = velocity x time
8
Q
What is the difference when there is a bar above the v in d = vt and s = vt ?
A
It would be called average speed and average velocity.
9
Q
What does T stand for when its in the units?
A
Terra x10 to the 12
10
Q
What does G stand for when its in the units?
A
Giga x10 to the 9
11
Q
What does M stand for when its in the units?
A
Mega x10 to the 6
12
Q
What does K stand for when its in the units?
A
Kila x10 to the 3
13
Q
What does m stand for when its in the units?
A
milla x10 to the -3
14
Q
What does weird M stand for when its in the units?
A
micro x10 to the -6
15
Q
What does n stand for when its in the units?
A
nano x10 to the -9
16
Q
What does P stand for when its in the units?
A
pico x10 to the -12
17
Q
How to work out the direction?
A
SOH CAH TOA. Work out the angle and add it to 0, 90, 180 or 270
18
Q
What is acceleration?
A
The change in velocity per second.
19
Q
What does this equation stand for a=v-u/t
A
acceleration=final velocity-initial velocity/time
20
Q
How to work out the distance on a speed time graph.
A
Work out the area under the line
21
Q
What does a line going up on a velocity time graph mean?
A
constant acceleration
22
Q
What does a line going down on a velocity time graph mean?
A
constant deceleration
23
Q
What does a straight line on a velocity time graph mean?
A
constant velocity
24
Q
What can happen if the forces on an object are unbalanced:
A
It may change speed
It may change direction
It may turn
It may change shape
25
What are some contact forces?
Friction
Drag
Air resistance
Surface tension
Up thrust
26
What are some non - contact forces?
Weight
Electrostatic
Magnetism
27
What could the aim and method be to do an experiment on weight and mass?
Aim: Investigate the relationship between mass and weight.
Method: Measure the weight of a variety of masses using a mass balance and a newton meter.
28
How to work out gradient:
gradient = vertical / horizontal
29
What is newtons second law equation?
F = ma
30
What does F = ma stand for?
Unbalanced force = mass x acceleration
31
What does the fish stand for: ( X
Proportionality
32
What is terminal velocity?
Maximum constant velocity
33
What are resultant forces?
The resultant forces is the overall force acting.
34
What are free body diagrams for?
To show the forces acting on an object.
35
What is gravitational field strength?
The gravitational force per unit mass. g=W/m
36
What is mass?
Mass is the quantity of particles in an object, in kilograms. m=W/g
37
What is weight?
Weight is the force due to gravity acting on the object, in Newtons. W=mg
38
How to work out unbalanced forces and a good way to work it out?
Take away the force acting against it from the force. Draw a diagram.
39
What is newton's first law?
An object will remain at rest or in constant motion in a straight line unless acted upon by an unbalanced force.
40
What is inertia?
The tendency of an object to stay at rest or continue in constant motion.
41
What is work in energy terms?
The energy transferred when a force moves an object a distance. In Joules
42
What is the work equation?
Ew=Fd
Energy / work = force x distance
43
What is power?
The energy transferred per second. In Watts
44
What is 1W equal to?
1 joule per second
45
What is the equation to work out power?
P = E / t
Power = Energy / time
46
What is the equation to work out potential energy?
Ep = mgh
Change in potential energy = mass x gravitational feild x height
47
What is the equation to work out kinetic energy?
Ek=0.5mv^2
Kinetic energy = 0.5 x mass x velocity^2
48
What does the area under velocity time graphs tell us?
By sketching a velocity time graph of an object moving vertically we can calculate the height.
49
State 3 things about projectile motion.
- Objects moving with projectile motion are moving horizontally and vertically.
- They have constant vertical acceleration of 9.8ms-2 toward the ground. a=v-u/t
- They have constant horizontal velocity. d=vt
50
What is the order of the planets and dwarf planets from the sun?
Sun
Mercury
Venus
Earth
Mars
Jupiter
Saturn
Uranus
Neptune
Ceres
Pluto
Haumea
Makemake
Eris
51
What are some uses of satellites?
Weather
GPS - Navigation
Communication
Military
Mapping / Photography
Exploration (Space Telescopes)
52
State 4 things about geostationary satellites.
- Obital period of 24 hours
- An altitude of 36,000km
- It orbits the same point
- Is useful for communication
53
What are parabolic reflectors?
Satellite dishes
54
Why do parabolic reflectors have curved reflectors?
To increase the signal strength by focusing it on one point.
55
What do satellites behave as?
Projectiles
56
How do satellites work as projectiles?
As they fall, the surface of the Earth curves away from them.
57
What is an ion drive?
An ion drive produces a small unbalanced force over a long period of time. This can cause a spacecraft to continue accelerating until it reaches a very high velocity.
58
What force do we have none in space but a lot on Earth?
Friction
59
What 2 things are very hard to do in space?
Manoeuvring
Maintaining sufficient energy
60
What is a gravity assist?
A gravity assist uses the gravitational force of a fast moving asteriod, moon or planet like a catapult, to accelerate a spacecraft.
61
What is a challenge for manned missions in space?
Life support
62
What is a solution for maintaining sufficient energy in space?
Using solar cells that vary in areas with the distance from the sun.
63
What are some life support requirement for space?
- Food
- Oxygen
- Water
- Health and wellbeing
- Heat
64
What are the 3 risks of space travel?
- Fuel load on take off
- Exposure to ionising radiation
- Re - entering
- Pressure differential
65
What is used to slow down the re - entering to the atmosphere?
Parachutes
66
What is used to stop the heat from frying the people inside the rocket while re - entering?
Heat shields
67
What do you need to safely re - enter the atmosphere?
Parachutes
A suitable angle of re - entry
68
What is a light year?
The distance travelled be light in a year
69
What makes images from telescopes on Earth unclear?
Weather, light pollution, turbulence.
70
What is wrong with telescopes on Earth?
- Unclear images
- Most types of electromagnetic radiation does not reach earth
- People can't observe space 24 / 7
71
Why does electromagnetic radiation not reach Earth?
They are absorbed be the atmosphere
72
Why are telescopes better in space?
- The images are less blury
- The images catch light that we can't see
- It can look at it 24 / 7
73
What is the stellar spectra?
The colour of stars indicates their surface temperature.
Red - coolest
Blue - hottest
74
What does a full spectrum of light from a star include?
Every wavelength
75
State things about the star spectrum.
- A full spectrum of light includes every wavelength
- When light passes through the outer regions of the star some wavelengths are absorbed by atoms and ions
- The line spectra from stars and galaxies can be compared with the line spectra from elements to know their composition
76
What can be detected by the retina (eye)?
Visible light
77
What can be detected by photodiode?
Infrared, visible light
78
What can be detected by photographic film?
Visible light, X - rays
79
What can be detected by aerial?
Microwaves, radio
80
What can be detected by fluorescent materials?
Ultraviolet
81
What can be detected by CCD?
Visible light
82
What is the approximate age of the universe?
14 billion years
83
What was the beginning of space and time?
All matter in the universe was contained in a tiny region that was extremely hot and dense (a singularity), that expanded rapidly outwards.
84
What happens to the line spectra as we look at galaxies farther and farther away?
The line spectra shifts towards the red end of the spectrum.
85
What is electrical charge?
When you rub 2 insulating materials, electrons are transferred from one to the other. This gives both a charge electrically charged objects attract or repel each other.
86
Whats a thing electrostatic forces are used for and how it works?
They can be used for photocopiers and it works by a sheet of paper being brought into contact with the drum surface and a charge is applied to the paper then the image is put on it.
87
What is electrical current?
The electrical charge transferred per unit of time. I = Q / t
88
What is the charge equation?
Q = It
charge = current x time
89
What are some rules about electrical current?
- It can only flow through conductors
- The higher resistance, the lower the current
- It is measured in amps
90
What is another name for voltage?
potential difference
91
What is the difference between A.c. and D.c.?
A.c. - alternating current repeatedly changes direction
D.c. - direct current flows in one direction around a circuit
92
What can a oscilloscope be used for?
To show the changing voltage of an electrical source.
93
What is mains electricity?
An alternating current supply (A.c.). The current constantly changes direction. Voltage alternates between positive and negative values. The domestic electricity supply has a frequency of 50Hz and is 230V.
94
What is potential difference?
The voltage of the supply is a measure of the energy given to the electrons (charge carriers) in a circuit.
95
What does a circuit need?
voltage for current to flow
96
What is 1V equal to?
1 J / C (1 coulomb of charge carries 1 J of energy)
97
How are electric field lines drawn?
From positive charges to negative charges. Lines never cross.
98
State things about batteries.
- An electric field in a conducting wire.
- There is a potential difference (voltage) across the positive and negative terminals
- Electrons (charged particles) in an electric field experience a force
- This force pushes the current around the circuit
99
State 3 things about series circuits.
- One loop
- Current is the same everywhere Is=I1=I2..
- Voltage is shared Vs=V1+V2...
- The resistance is added from each resistor RT = R1 + R2...
100
State 3 things about parallel circuits.
- More than one loop
- Current is split across branches Ip=I1+I2...
- Voltage is same everywhere Vp=V1=V2...
- Adding resistors will reduce the resistance because there are more paths to go 1/RT=1/R1+1/R2. or RT=(R1-1+R2-1)-1
101
What is the equation to work out the voltage across one component in a circuit?
V1 = (R1/RT) Vs
102
What is the equation to work out the voltage and resistance over 2 components?
V1/V2 = R1/R2
103
What does a photoresistor do in a circuit?
As the light intensity increases the resistance decreases.
104
What does a thermistor do in a circuit?
As the temperature increases the resistance decreases.
105
What is the equation to work out the voltage?
V = IR
Potential Difference = Current x Resistance
106
How do you investigate Ohm's law?
Use a variable resistor to change the voltage and current.
107
What 3 components are used as electrical switches?
- Relays
- MOSFETS
- npn transistors
108
Give a brief description of a relay.
A relay consists of an electromagnet that can open or close a switch to another circuit. This is a safe way to control a circuit with a high voltage.
109
Give a brief description of a transistor.
A transistor is an electric switch. A transistor switches on at certain voltages. It usually switched on automatically by other electrical components in a potential divider circuit.
110
Give a brief description of a MOSFET.
A MOSFET is just a type of transistor. It switches on at a certain voltage. (Metal - Oxide Semiconductor Field - Effect Transistor).
111
What do these letters stand for and their units:
d
v
t
s
a
R
distance (m)
speed or (final) velocity (ms-1)
time (s, hr)
displacement (m)
acceleration (ms-2)
resistance (_n_) (ohms)
112
What do these letters stand for and their units:
u
F
m
W
g
P
initial velocity (ms-1)
(unbalanced) force (N)
mass (g)
weight (N)
gravitational field strength (Nkg-1)
power (W)
113
What do these letters stand for and their units:
E
h
Q
I
V
energy (J)
height (m)
charge (C)
current (A)
voltage (V)
