PHYSICS PART 1 and 2 Flashcards Preview

AQA ADDITIONAL SCIENCE > PHYSICS PART 1 and 2 > Flashcards

Flashcards in PHYSICS PART 1 and 2 Deck (196):
1

What is velocity?

When something has both speed and direction
(m/s or km/h or mph)

2

What is acceleration?

A change in velocity
(m/s^2)

3

What is speed?

How fast you're going with no regard to direction
(m/s or km/h or mph)

4

What is force?

A push or pull that changes the way an object is moving or is shaped
(newtons)

5

What is mass?

The amount of matter in an object
(Kilograms)

6

What can reduce the acceleration for a particular force?

A greater/larger mass of an object

7

In distance time graphs, what does the gradient suggest?

The speed

8

In a distance time graph, what do flat sections suggest?

It is stationary and has stopped

9

In a distance time graphs, what does a straight uphill/downhill line suggest?

It is travelling at a steady speed

10

In a distance time graph, the steeper the graph...

The faster it's going

11

In a distance time graph, what do downhill sections suggest?

It is returning to its starting point

12

What do curves suggest on a distance time graph?

Acceleration or deceleration

13

What does an increasing gradient (steepening curve) suggest?

It's speeding up

14

What does a decreasing gradient (levelling off curve) suggest?

It slowing down

15

Distance formula

Distance (m)
=
Speed (m/s)

MULTIPLIED BY

Time (s)
(Rearrange for speed and time)

16

What can a change in velocity suggest?

A change in speed, direction, or BOTH

17

Acceleration formula

Acceleration (m/s^2)
=
Change in velocity (speed) (m/s)

DIVIDED BY

Time taken (s)

18

What does the gradient in a velocity time graph suggest?

Acceleration

19

What does a flat section suggest in a velocity time graph?

Steady speed

20

In a velocity time graph, the steeper the graph...

The greater the acceleration of deceleration

21

In a velocity time graph, what do uphill sections suggest? (/)

Acceleration

22

In a velocity time graph, what do downhill sections suggest? (\)

Deceleration

23

What does a curve in a velocity time graph suggest?

A change in acceleration

24

What does the area under any section of a velocity time graph suggest?

The distance travelled in that time interval

25

How can the velocity be given for a given time on a velocity time graph

Reading of the value off the correct axis

26

Gravitational force is the force between all...

Masses

27

What are the effects of gravity attracting masses?(2)

-It makes all things accelerate towards the ground with the same acceleration
-It gives everything a weight

28

What is weight?

The force of gravity pulling something towards the centre of the earth
(newtons)

29

How is weight measured?

Spring balance or newton metre

30

How is mass measured?

Using a mass balance

31

Weight formula

Weight (newtons)
=
Mass (kg)

MULTIPLIED BY

Gravitational field strength (N/kg)

32

What is the gravitational field strength on Earth?

Roughly 10 N/kg

33

What is the gravitational field strength on the Moon?

Roughly 1.6 N/kg

34

What is the resultant force?

The overall force on a point it on an object

35

The overall effect of forces, can decide what about the motion of an object? (3)

Whether it will:
-Accelerate
-Decelerate
-Stay at a steady speed

36

How can the resultant force be found if both forces work in the same direction?

You add them:
ForceX + ForceY= Resultant Force

37

How can the resultant force be found if both forces are working in opposite directions?

You subtract them:
ForceX - ForceY = Resultant Force

38

What can be suggested if the resultant force is 0? (2)

- a stationary object remains stationary
- a moving object continues at the same velocity

39

If a resultant force is acting upon an object it causes a...

Change in the objects velocity

40

When answering questions about resultant forces what should always be included in your answer?

The direction that the forces are pointing to
E.g 400N to the left in a positive direction

41

Who worked out the laws of motion?

Sir Isaac Newton

42

What are the laws of motion? (3)

- an object needs a force to start moving
- no resultant force means no change in velocity
- a resultant force means acceleration

43

If there is a non zero resultant force, what happens to the motion of the object?

It will accelerate in the direction of the force

44

A non zero resultant force always results in...

Acceleration or deceleration

45

The acceleration produced by a non zero resultant force can lead to...(5)

-Starting
-Stopping
-Speeding up
-Slowing down
-Changing direction

46

Why do we need a driving force to keep us travelling at a steady speed?

Because of air resistance and friction

47

Resultant force formula

Resultant force (newtons, N)
=
Mass (kg)

MULTIPLIED BY

Acceleration (m/s^2)

48

When two objects interact, the forces they exert on each other are...

Equal and opposite

49

If forces are always equal when 2 objects interact, how does anything move?

The forces are opposite and a different mass can cause one object to accelerate away faster (and in the opposite direction)

50

What effect does friction have on an object that has no force propelling on it?

It will always slow down and eventually stop (except in space)

51

Friction acts in which direction?

Opposite direction to the movement

52

To travel at a steady speed, the frictional force must...

Balance the driving force

53

When do you get friction? (2)

When two surfaces become in contact
When an object passes through a fluid (drag)

54

Most resistive forces are caused by...

Air resistance or drag

55

How can you reduce drag in fluids?

Keeping the shape of the object streamlined

56

An example of when the drag force is very high

Parachute

57

Drag increases as...

Speed increases

58

How do forces affect a parachutist?

-When they first set off, gravity is larger than than air resistance do they accelerate
-As the speed increases so does the air resistance and therefore the acceleration reduces
-The forces then become balanced and a terminal velocity is reached and will no longer accelerate, it will just fall at a slower steady speed

59

All objects flowing through ... reach a terminal velocity

Fluids

60

The terminal velocity of falling objects depends on their...(2)

Shape and area

61

On earth, why do things fall to the ground at different speeds?

Because air resistance acts on all objects different

62

Define total stopping distance

The distance covered in the time between the driver first spotting a hazard and the vehicle coming to a complete stop

63

Define stopping distance

The sum of the thinking and braking distance

64

Define reaction time

The time between the driver spotting a hazard and taking action

65

Define thinking distance

The distance the vehicle tracked during the drivers reaction time

66

What is thinking distance affected by? (2)

- how fast you're going
- how dopey you are
(tiredness, alcohol, drugs, careless attitude)

67

What is braking distance affected by? (4)

- how fast your going
- how good your breaks are
- how good the tyres are (min tread depth of 1.6mm)
- how good the grip is (this depends on:)
road surface, weather conditions and tyres

68

What is work done/energy transferred?

When a force moves an object through a distance
(joules)

69

Work done formula

Work done (joules)
=
Force (newtons, N)

MULTIPLIED BY

Distance (m)

70

What is gravitational potential energy?

The energy an object has because if its vertical position in a gravitational field
(Joules)

71

Gravitational potential energy formula

Gravitational potential energy (j)
=
Mass (kg)
MULTIPLIED BY
Gravitational field strength (N/kg)
MULTIPLIED BY
Height (m)

72

What is kinetic energy?

The energy of movement
(Joules)

73

Kinetic energy formula

Kinetic energy (joules)
=
1/2
MULTIPLIED BY
Mass (kg)
MULTIPLIED BY
Speed^2 (m/s)

74

The kinetic energy of something depends on...(2)

Mass and speed, the faster/bigger these are the higher the kinetic energy will be

75

Kinetic energy transferred is what?

Work done
(Joules)

76

Kinetic energy transferred formula

Kinetic energy transferred (j)
=
Work done by brakes (j)
Or
1/2(mass)x(speed^2)=max braking force(N)x braking distance(N)

77

Conservation of energy

Energy can never be created or destroyed, only converted into different forms

78

Potential energy lost means...

Kinetic energy is gained

79

Why do meteors never completely hit the earth?

They have very high kinetic energy
Friction (due to collisions) causes some of the energy to transfer into heat and sound
The temperature become so extreme that most meteors burn up and so never hit the ground

80

What is elastic potential energy?

When work is done to an object to change its shape, the energy is not lost but stored as elastic potential energy.
It then is converted back into kinetic energy where the force is done and as a result for e.g an elastic band bounces back

81

The extension of an elastic object is ... to the force

Directly proportional

82

Force formula

Force (N)
=
Spring constant (N/m)

MULTIPLIED BY

Extension (m)

83

What is the limit of proportionality?

The maximum force that the elastic object can take and still extend proportionally

84

What is power?

The rate of energy transferred
(Watts or j/s)

85

Power formula

Power (Watts or j/s)
=
Work done/energy transferred (j)

DIVIDED BY

Time taken (s)

86

One watt is equal to...

1 joule of energy transferred per second

87

How can you calculate the power output of a person? (2)

- The timed run upstairs

- The time acceleration

(Must repeat these experiments and calculate an average for accurate results)

88

What is momentum?

Properly of moving objects
It has a size and direction (but not speed)
(Kg m/s)

89

Momentum formula

Momentum (kg m/s)
=
Mass (kg)

MULTIPLIED BY

Velocity (m/s)

90

An object has a higher momentum if it has...(2)

A greater mass of an object
A greater velocity

91

Conservation of momentum

Momentum before = momentum after

92

When a force acts on an object it causes a...

Change in momentum

93

A larger force acting on an object causes a...

Faster change of momentum (and so greater acceleration)

94

How do breaks reduce kinetic energy?

Work is done when the breaks are applied
Brakes transfer energy into heat and sound

95

What are regenerative brakes?

Use the system that drives the vehicle to do most of the braking
They store energy of braking instead of wasting it
It causes the motor to run backwards so the wheels are slowed down

96

How do crumple zones lessen the force on passengers during a crash?

At the front and back, they crumple on impact
Kinetic energy is converted to other forms as the car body changed shape
They increase the impact time, decreasing the force produced

97

How do side impact bars reduce force on passengers during a crash?

They direct kinetic energy away from passengers to areas such as crumple zones

98

How can seat belts reduce forces on passengers during a crash?

They stretch causing an increase in time
This reduces the forces acting on the chest
Some kinetic energy is absorbed by the belt stretching

99

How do air bags reduce forces felt by passengers in a crash?

They slow you down more gradually
Stop you from hitting hard surfaces

100

What determines how powerful a car is? (2)

Size of car engine
Design of car engine

101

What is static electricity?

Charges that are not free to move e.g. In insulating materials

102

How are electric shocks caused?

If the charges are not free to move they can build up in one area which often results in a shock when they eventually do move

103

How can an insulting materials charge change?

When certain insulating materials get rubbed together the (negatively charged) electrons are rubbed off and moved onto the other material
This makes it gain a positive static charge and the other gain a negative static charge

104

Example of static charge experiment

Polythene and acetate rod with cloth
Polythene rod - rod loses electrons and becomes positively charged, the cloth gains electrons and is now negatively charged
Acetate rod - rod gains electrons and becomes negatively charged, cloth loses electrons and becomes positively charged

105

Like charges...

Repel

106

Opposite charges...

Attract

107

Electrical charges can move easily though materials called...

Conductors e.g. Metals

108

What is current?

The flow of electric charge around a circuit, current only flows if there is a voltage
(Ampere, A)

109

What is voltage/ potential difference?

The driving force that pushes the current around
(Volts, V)

110

What is resistance?

Anything that slows the flow in the circuit down
(Ohms)

111

The greater the resistance for a given voltage...

The smaller the current

112

Total charge though a circuit depends on... (2)

Current and time

113

Current formula

Current (A)
=
Charge (Coulombs, C)

DIVIDED BY

Time (seconds)

114

Potential difference formula

Voltage (Volts)
=
Work done (joules)

DIVIDED BY

Charge (Amperes)

115

What does the "standard test circuit" allow you to find out?

The resistance of a component

116

The ammeter (3)

1. Measures the current (amps)
2. Placed in series
3. Can be placed anywhere, except in parallel

117

Voltmeter (2)

1. Measures voltage (volts)
2. Placed in parallel around component NOT variable resistor or battery

118

5 key points about the "standard test circuit"

1. Used to test components and create V-I graphs
2. Component, ammeter and variable register are in series and therefore any order. Voltmeter only in parallel around component.
3. Varying the variable resistor alters current
4. You can take several readings from the ammeter and voltmeter
5. Plotting the value for current and voltage on a V-I graph allows you to going the resistance

119

Electrons move wrong circuits from...

-ve to +ve

120

What do V-I graphs show you?

How the current varies as you change the voltage

121

What 3 V-I graphs should you know?

1. Different resistors
2. Filament lamp
3. Diode/LED

122

What does the "Different Resistors" V-I graph show?

(Straight diagonal line)
The current through a resistor is DIRECTLY PROPORTIONAL to the voltage.
Differ resistors have different resistances

123

What does the "Filament lamp" B-I graph show?

(S shaped curve)
As the temperature increases, the resistance increases
As temp increases particles in the metal gain more energy and vibrate, making it harder for electrons to flow (so resistance increases)

124

What does the "Diode/LED" V-I graph show?

Current will only flow in one direction, in a forward direction
Little current flows in the opposite direction so the resistance in the opposite direction is very high

125

Resistance increases with...

Temperature

126

Who does an increase in temperature increase the resistance?

When a charge flows, energy can be transferred to heat which makes the resistor heat up
The ions then vibrate more making it hard for the charge carrying electrons to get through the resistor

127

Why is there a limit to the amount of current that can flow in resistors?

More current means an increase in temperature
This means an increase in resistance
Therefore the current decreases again
(This causes the graph for the filament lamp to level off at high currents)

128

Voltage formula

Potential difference (volts, v)
=
Current (amps, a)

MULTIPLIED BY

Resistance (ohms)

129

Diode features (4)

-Special device made from a semi conductor material (such as silicon)
-Regulates the voltage in circuits
-Allows current to flow in only one direction
-Useful in electronic circuits

130

LED(Light emitting diode) features (4)

- emits light when current flows through it in a forward direction
- uses a smaller current than most forms of lighting so are quite common
- indicate the presence of a current (e.g. Used in TVs to show they are switched on)
- also used for numbers on digital clocks, traffic lights and remote controls

131

LDR(light dependent resistor) features (4)

- dependent on the intensity of light
- in bright light, the resistance falls
- in darkness, the resistance is highest
- uses include automatic night lights, outdoor lighting and burglar detectors

132

Thermistor features (4)

- temperature dependant resistor
- when hot, the resistance falls
- when cold, the resistance increases
- uses as temperature detectors (e.g. car engine temperature sensors and electronic thermostats)

133

Series circuits RULES (5)

1. Removing a component breaks the circuit, everything stops
2. Voltage is shared
(total voltage = V 1+ V2...)
3. Current is the same everywhere (A1=A2)
4. Resistance adds up (R = R1 + R2)
5. Cell voltages add up

134

Parallel circuits RULES

1. Each component is connecting separately, removing one will not affect the others
2. Voltage is the same (V1 = V2 = V3)
3. Current is shared (A = A1 + A2)
4. The total current entering a junction is equal to the total current leaving
5. Ammeters are an exception and are connected in series even if the circuit is parallel

135

Mains voltage is...

230 Volts

136

Example of when series circuits are used

Christmas fairy lights

137

Parallel connection is essential in a car to give which features? (2)

- everything can be turned on and off separately
- everything always gets the full voltage from the battery

138

Why do alternating currents work?

Because to transfer energy, it doesn't matter which way the charge carriers are going

139

What is the UK mains supply?

Approx. 230 Volts

140

What is an AC supply?

Alternating current
The current is constantly changing direction

141

What is the frequency of the AC mains supply?

50 cycles per second
Or 50 Hertz

142

What is DC?

Direct current, supplied by cells and batteries
Current always flows in the same direction

143

How can electricity supplies be seen?

On an oscilloscope screen

144

What is a cathode ray oscilloscope? (CRO)

Similar to a voltmeter

145

Voltage for AC supply in an oscilloscope

If you plug an AC supply into the oscilloscope
-A trace appears on the screen that shows how the voltage changes with time
(The pattern is regular)
( looks like a wave)

146

What does the trace look like when you plug a DC supply into an oscilloscope?

A straight line

147

The vertical height of the AC trace at any point shows...

The input voltage
(Measure the height to find voltage)

148

How do you find the voltage for DC?

The distance from the straight line trace to the centre line

149

What does the gain dial do?

Controls how many volts each cm division represents on the vertical axis

150

What does the timebase dial control?

How many milliseconds each division represents on the horizontal axis (1ms=0.001s)

151

What is a time period?

The time to complete one cycle (a whole wave)

152

X axis on the oscilloscope is

Time

153

Y axis on the oscilloscope is

Voltage

154

Frequency formula

Frequency (Hz)
=
1
DIVIDED BY
Time period (seconds)

155

Mains supply is

AC

156

Battery supply is

DC

157

AC's current can be increased/decreased using a

Transformer

158

The lower the current in power transmission lines

The less energy is wasted (as heat)

159

Hazards in the home (9)

1. Long cables
2. Frayed cables
3. Cables touching something hot/wet
4. Water near sockets
5. Shoving items into sockets
6. Damaged plugs
7. Too many plugs in one socket
8. Lighting sockets without bulbs
9. Appliances with no covers in

162

What does the Earth Pin do?

Connects to Earth wire
Transfers energy away from device if there is a fault

163

What does the neutral pin do?

Connects to the neutral wire
Completes the circuit
Voltage of 0

164

What does the live pin do?

Connects to live wire
Provides the energy to the device
Voltage of 230V

165

Earth wire

Protects the wiring
For safety
Works with a fuse to prevent shocks/fires

166

Electricity flows normally through which wires?

Live and neutral only

167

Live wire

Alternates between a positive and negative voltage

168

Each wire has...

A core of copper
A coloured plastic covering

169

Most cables have ... wires

3

170

The separate wires are called

The Earth wire (green and yellow)
The Neutral wire (blue)
The Live wire (brown)

171

Safety features of wiring inside a plug and cable (4)

- the correct wire must be tightly screwed to the correct pin
- no bare wires should be shown inside the plug
- the cable grip must be tightly fastened over the cable outer layer
- thicker cables have less resistance and carry more current

172

Why are the metal parts of the plug made it brass or copper?

Good conductors

173

Why is the case, case grip/ insulation made of rubber or plastic?

Good insulators
Flexible

174

Earthing and fuses prevent...

Electrical overloads

175

How does the Earth wire along with a fuse/circuit breaker work?

- if a fault eg live wire touches metal casing, then too big a current flows though live wire, case and out down the Earth wire because the case is heavily earthed
- this melts the fuse as it goes beyond the fuse rating so the circuit gets broken
- this makes it impossible to get an electric shock and prevents the risk of a fire

176

Why does the fuse rating increase with cable thickness?

The larger the current, the thicker the cable you need to carry it

177

Define earthing

The case must be attached to an Earth wire

178

Why are appliances with metal cases earthed?

To reduce the risk of an electric shock

179

An earthed wire can never...

Become live

180

When is an appliance double insulated?

If it has a plastic casing with no metal showing

181

Anything that is double insulated doesn't require a ... wire

Earth

182

What are circuit breakers?

Electrical safety devices used in circuits to protect it if too much current flows

183

Advantages of circuit breakers over fuses

They can be reset by flicking the switch (instead of being replaced)
They are quicker

184

Advantages of fuses over circuit breakers

They are much cheaper

185

Name a type of circuit breaker

Residual Current Circuit Breaker (RCCBs)

186

Explain how RCCBs work

Detects a difference in current and cuts of power by opening a switch
Much faster than fuses
Time is not wasted on melting fuses so it's safer
Work for small current changes
Effective

187

ALL Resistors produce ... when a ... flows through them

Heat, current

188

Why do resistors produce heat when a current flows through them?

Electrical energy is converted to heat energy

189

Filament bulbs

Works by passing a current through a thin wire and heating it up so it glows
It therefore wastes a lot of energy as heat

190

If an appliance is efficient...

It wastes less energy

191

How can you make sure as little energy is wasted on heat?

Buy energy efficient electrical appliances

192

Energy transferred formula

Energy transferred (J)
=
Power (w)

MULTIPLIED BY

Time (seconds)

193

Electrical power formula

Power (w)
=
Current (a)

MULTIPLIED BY

Voltage (v)

194

Fuse needed formula

Fuse (a)
=
Power (w)

DIVIDED BY

Voltage (v)

195

Energy transformed formula

Energy transformed (j)
=
Electrical charge (c)

MULTIPLIED BY

Voltage (v)

196

The bigger the change in voltage, the ... energy is transferred for a given amount of charge

More

197

Why did the plum pudding experiment take place in a vacuum chamber?

So the alpha particles do not bounce or come into contact with the air particles

198

What was the plum pudding experiment?

Alpha particles were fired onto a thin gold foil in the expectancy they would be slightly deflected by the electrons