General physics Flashcards
1
Q
What are rulers used for?
A
To measure small distances
2
Q
What unit are rulers able to measure to?
A
mm
3
Q
What is the accuracy of a ruler?
A
0.1 cm
4
Q
What is a micrometer screw gauge used for?
A
To measure very small distances that a ruler cannot
5
Q
What unit is a micrometer screw gauge able to measure to?
A
mm
6
Q
What is the accuracy of a micrometer screw gauge?
A
0.01 mm
7
Q
What are vernier calipers used for?
A
To measure very small distances that a ruler cannot
8
Q
What unit are vernier calipers able to measure to?
A
mm
9
Q
What is the accuracy of a vernier caliper?
A
0.02 mm
10
Q
When measuring very small distances which apparatus is most appropriate?
A
Micrometer screw gauge
11
Q
What is used to measure large distances?
A
Tape measure
12
Q
What unit is a tape measure able to measure to?
A
m
13
Q
What is used to measure very large distances?
A
Trundle wheel
14
Q
What unit is a trundle wheel able to measure to?
A
m
15
Q
What is used to measure volume?
A
Measuring cylinder
16
Q
What 2 things does measure cylinder measure?
A
- Volume of a liquid
2. Volume of an irregular-shaped object
17
Q
What are used to measure intervals of time
A
Stop-clocks and stopwatches
18
Q
How do you measure things that would be difficult to get accurate readings?
A
- Measure multiples
2. Average
19
Q
Define speed
A
Change in distance per unit time
20
Q
What is the formula for speed?
A
Distance ÷ time taken
21
Q
Define velocity
A
Displacement per unit time
22
Q
What is the formula for velocity?
A
Displacement ÷ time taken
23
Q
Define acceleration
A
Change in velocity per unit time
24
Q
What is the formula for acceleration?
A
Change in velocity ÷ time taken
25
What does the gradient of a distance-time graph represent?
Speed
26
What does the gradient of a speed-time graph represent?
Acceleration
27
What does the area underneath a speed-time graph with constant acceleration represent?
Distance
28
What is deceleration?
Negative acceleration
29
What is the acceleration of free fall for a body near to the Earth?
Constant at 10 m/s
30
What is mass?
The amount of matter contained in an object
31
What is weight?
A gravitational force
32
What is the unit of mass?
kg
33
What is the unit of weight
N
34
What does mass resist?
Change in motion or change in direction
35
What is the resistance to change in motion or change in direction by mass called?
Inertia
36
What is the effect of a gravitational field on a mass?
Weight
37
Exam tip ; )
1. In the absence of air resistance, all objects fall with the same acceleration, regardless of their mass
2. So long as air resistance remains insignificant, the speed of a falling object will increase at a steady rate, getting larger the longer it falls for.
38
Describe terminal velocity
1. There is a downwards unbalanced force and the skydiver accelerates
2. As the skydiver speeds up, the air resistance increases
3. Eventually the air resistance balances the weight and so the skydiver travels at a constant speed
4. When the parachute is opened the increase air resistance on the parachute creates an upwards unbalanced force, making the parachuting the slow down
39
What term is used when air resistance and weight cause a body to move at constant speed?
Terminal velocity
40
How can weight (and hence mass) be compared?
Using a balance
41
What is the formula for density?
ρ = mass ÷ volume
42
Which object will float based on density?
The less dense object will float on a more dense object
43
What are 3 effects of forces?
1. Change in size
2. Change in motion
3. Change in direction
44
What is Hooke's Law?
The extension of a spring is proportional to the applied force
45
What is the formula for Hooke's Law?
F = kx
| *where k is the spring constant
46
What is the limit of proportionality?
Point at which load and extension are no longer proportional
47
What is the elastic limit?
Point at which the spring will no longer return to its original position after being stretched
48
What is the formula for force?
F = ma
49
Exam tip ; )
A relationship is said to be proportional if the graph is a straight line going through the origin.
If a graph is a straight line but does not go through the origin the relationship is said to be linear.
50
Describe circular motion
An object at steady speed in circular orbit is always accelerating as it's changing direction but gets no closer to the center
51
What quantity stays constant for circular motion?
Speed
52
What causes circular motion
A force acting at 90 degrees to an object's direction of travel
53
Which factors affect the force needed to make something follow a circular path?
1. Mass
2. Speed
3. Radius
54
How does mass affect force that makes an object follow a circular path?
A greater mass requires greater force
55
How does speed affect force that makes an object follow a circular path?
A greater speed requires greater force
56
How does radius affect force that makes an object follow a circular path?
A greater radius requires greater force
57
What is centripetal force?
A force acting towards the centre of a circle
58
What is centrifugal force?
A force acting away from the centre of a circle
59
What is the result of a body not having a resultant force?
1. Continues to travel at constant speed in a straight line
| 2. Stays at rest
60
What is friction?
The force between two surfaces which impedes motion and results in heating
61
What is a form of friction?
Air resistance
62
What is a moment ?
A measure of the turning effect of a force
63
What increases the moment of a force?
1. Increasing force
| 2. Increasing distance from a pivot
64
What is the formula for moment?
Nm = Force × perpendicular distance from the pivot
65
What is the principle of moments?
For a system to be balanced, the sum of clockwise moments must be equal to the sum of anticlockwise moments
66
What are 2 conditions for equilibrium?
1. No resultant force
| 2. No turning effect
67
What is the centre of mass?
The point through which the weight of an object acts
68
Where is the centre of mass of a symmetrical object found?
The point of symmetry
69
Describe an experiment to find the centre of mass of a plane lamina
1. Make a hole in the lamina
2. Hang it so it can swing freely
3. Hang a plumb line in the hole
4. Use a pencil to draw a vertical line from the pivot
5. Repeat the process, suspending the object from a different point
6. Centre of mass is locating where the lines cross
70
When is an object stable?
When its centre of mass lies above its base
71
When is an object unstable?
When its centre of mass does not lie above its base
72
How does an object's centre of mass affect its stability?
A lower centre of mass will make the object more stable
73
What can an object's stability be increased?
1. Increase surface area
| 2. Make the object shorter
74
What is a scalar?
A quantity with only magnitude
75
What is a vector?
A quantity with both magnitude and direction
76
What are 4 examples of scalar quantities?
Distance, time, energy and mass
77
What are 4 examples of vector quantities?
Acceleration, momentum, displacement and force
78
How do you find the resultant vector when 2 vectors point to different direction?
1. Draw an arrow representing the first vector
2. Starting at the tip of the first vector, draw an arrow representing the second vector
3. Resultant vector is found by going from the tail of the first vector to the tip of the second vector
79
What is the formula for momentum?
p = mass × velocity / mv
80
What are 2 formulas for impulse?
1. impulse = force × time
| 2. impulse = change in momentum / Ft = mv - mu
81
What is the principle for the conservation of momentum?
In the absence of external forces, the total momentum of a system remains the same
82
Give 6 examples of energy
1. Kinetic
2. Gravitational potential
3. Internal
4. Elastic (strain)
5. Chemical
6. Nuclear
83
What is the formula for kinetic energy?
kinetic energy = 0.5mv^2
84
What is the formula for gravitational potential energy?
gravitational potential energy = mg∆h
85
What is the principle of conservation of energy?
Energy cannot be created or destroyed, it can only change from one form to another
86
*Bonus question*
| What is energy?
The capacity of something to do work
87
What are 4 ways in which energy is transferred during processes and events?
1. Forces (mechanical working)
2. Electrical currents (electrical working)
3. Heating
4. Waves
88
What 3 forms of energy end up dissipating?
Heat, sound and light
89
Describe how electricity is obtained from fuels
1. Fuels are burnt to produce heat
2. Heat is used to convert water into steam
3. Steam turns turbines
4. Turbines generate electricity
90
Describe how electricity is obtained from water
1. Hydroelectric and tidal power use GPE of water
2. This turns turbines
3. Turbines generate electricity
91
Describe how electricity is obtained from waves
1. Kinetic energy of waves is used to turn turbines
| 2. Turbines generate electricity
92
Describe how electricity is obtained from geothermal resources
1. Heat from underground rocks used to generate steam
2. Steam turns turbines
3. Turbines generate electricity
93
Describe how electricity is obtained by nuclear fission
1. Uranium atoms split by firing neutrons at them
2. Releases heat used to generate steam
3. Steam turns turbines
4. Turbines generate electricity
94
Describe how electricity is obtained from light from the Sun
Photovoltaic cells use light to generate electricity
95
Describe how electricity is obtained from heat from the Sun
Heat is used to warm water moving through black pipes
96
Describe how electricity is obtained from wind
1. Kinetic energy of wind used to turn wind turbines
| 2. Wind turbines generate electricity
97
What are the advantages of using chemical energy stored in fuel to generate electricity?
1. Cost-effective
2. Produce energy on a large-scale
3. Reliable
98
What are the disadvantages of using chemical energy stored in fuel to generate electricity?
1. Produces greenhouse gases
| 2. Non-renewable
99
What are the advantages of using water to generate electricity?
1. Renewable
2. No greenhouse gases produced
3. Produces energy on a large-scale
4. Hydro is reliable
100
What are the disadvantages of using water to generate electricity?
1. Expensive to build
| 2. Tidal is not reliable
101
What are the advantages of geothermal resources used to generate electricity?
1. Reliable
| 2. Cost-effective
102
What are the disadvantages of geothermal resources used to generate electricity?
1. Does not produce energy on a large-scale
2. Produces greenhouse gases
3. Non-renewable
103
What are the advantages of generating electricity by nuclear fission?
1. Reliable
2. Produces energy on a large-scale
3. No greenhouse gases produced
104
What are the disadvantage of generating electricity by nuclear fission?
1. Produces radioactive waste
| 2. Expensive to build
105
What are the advantages of using heat and light from the Sun to generate electricity?
1. Renewable
| 2. No greenhouse gases produced
106
What are disadvantages of using heat and light from the Sun to generate electricity?
1. Unreliable
2. Does not produce energy on a large-scale
3. Expensive to set up
107
Which 3 energy resources is the Sun not a source of?
1. Geothermal
2. Nuclear
3. Tidal
108
By what process does the Sun release energy?
Nuclear fusion
109
What is efficiency?
How much useful work is done from the total energy supplied
110
What is the formula for efficiency in terms of energy?
Efficiency = useful energy output ÷ total energy input
111
What is the formula for efficiency in terms of power?
Efficiency = useful power output ÷ total power input
112
What is work done equal to?
Energy transferred
113
What 2 things are used to calculate work done?
1. Magnitude of the force
| 2. Distance moved in the direction of the force
114
What is the formula for work done?
W = Fd = ∆E
115
What is the unit for work done?
Joules (J) or Newtonmetres (Nm)
116
What is power?
Amount of energy transferred per second
117
What is the formula for power?
P = ∆E/t
118
What does kilo mean?
1,000
119
What does mega mean?
1,000,000
120
What does giga mean?
1 billion
121
What is pressure?
The concentration of a force
122
What is the formula for pressure?
p = F/A
123
What is used to measure atmospheric pressure?
Mercury barometer
124
What is used to measure pressure difference?
Manometer
125
What does the height difference show?
Extra pressure the gas supply has
126
What is the formula of pressure in liquids?
p = hρg
127
What are 2 factors of pressure in liquids?
1. Depth of the liquid
| 2. Density of the liquid
128
State Boyle's Law?
For a fixed mass of gas at constant temperature, the pressure is inversely proportional to volume
