AQA Additional Science

1
AQA Additional Science
Physics 2
A slideshow that covers the entire AQA 2006
Syllabus Physics 2 Module
W Richards
2
Distance, Speed and Time

1. Seb walks 200 metres in 40 seconds. What is his
   speed?
2. Lucy covers 2km in 1,000 seconds. What is her
   speed?
3. How long would it take Freddie to run 100 metres
   if he runs at 10m/s?
4. Sue travels at 50m/s for 20s. How far does he
   go?
5. Hannah drives her car at 85mph (about 40m/s).
   How long does it take her to drive 20km?

3
Speed vs. Velocity
Speed is simply how fast you are travelling
Velocity is speed in a given direction (a
vector quantity)
4
Acceleration

1. A cyclist accelerates from 0 to 10m/s in 5
   seconds. What is her acceleration?
2. A ball is dropped and accelerates downwards at a
   rate of 10m/s2 for 12 seconds. How much will the
   balls velocity increase by?
3. A car accelerates from 10 to 20m/s with an
   acceleration of 2m/s2. How long did this take?
4. A rocket accelerates from 1,000m/s to 5,000m/s in
   2 seconds. What is its acceleration?

5
Velocity-time graphs
80 60 40 20 0




Velocity m/s
T/s
10 20 30 40 50
6
80 60 40 20 0




Velocity m/s
T/s
10 20 30 40 50

1. How fast was the object going after 10 seconds?
2. What is the acceleration from 20 to 30 seconds?
3. What was the deceleration from 30 to 50s?
4. How far did the object travel altogether?

7
Balanced and unbalanced forces
Reaction
Consider a camel standing on a road. What forces
are acting on it?
These two forces would be equal we say that
they are BALANCED. The camel doesnt move
anywhere.
Weight
8
Balanced and unbalanced forces
Reaction
What would happen if we took the road away?
The camels weight is no longer balanced by
anything, so the camel falls downwards
Weight
9
Introduction to Forces
A force is a push or a pull. Some common
examples
Air resistance/drag a contact force that acts
against anything moving through air or liquid
Weight (mg) pulls things towards the centre of
the Earth
_____ a contact force that acts against
anything moving
Upthrust keeps things afloat
10
Air Resistance
Air resistance is a force that opposes motion
through air. The quicker you travel, the bigger
the air resistance
The same applies to a body falling through a
liquid (called drag or upthrust).
11
Balanced and unbalanced forces
12
Balanced and unbalanced forces
1) This animal is either ________ or moving with
_____ _____
2) This animal is getting _________
3) This animal is getting _______.
4) This animal is
13
Resultant Force
Calculate the resultant force of the following
500N
100N
700N
600N
50N
700N
700N
800N
800N
200N
100N
14
Force and acceleration
If the forces acting on an object are unbalanced
then the object will accelerate, like these
wrestlers
Force (in N) Mass (in kg) x Acceleration (in
m/s2)
15
Force, mass and acceleration

1. A force of 1000N is applied to push a mass of
   500kg. How quickly does it accelerate?
2. A force of 3000N acts on a car to make it
   accelerate by 1.5m/s2. How heavy is the car?
3. A car accelerates at a rate of 5m/s2. If it
   weighs 500kg how much driving force is the engine
   applying?
4. A force of 10N is applied by a boy while lifting
   a 20kg mass. How much does it accelerate by?

16
Terminal Velocity
Consider a skydiver

1. At the start of his jump the air resistance is
   _______ so he _______ downwards.

2) As his speed increases his air resistance will
_______
3) Eventually the air resistance will be big
enough to _______ the skydivers weight. At this
point the forces are balanced so his speed
becomes ________ - this is called TERMINAL
VELOCITY
Words increase, small, constant, balance,
accelerates
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Terminal Velocity
Consider a skydiver

• 4) When he opens his parachute the air
  resistance suddenly ________, causing him to
  start _____ ____.

5) Because he is slowing down his air resistance
will _______ again until it balances his
_________. The skydiver has now reached a new,
lower ________ _______.
Words slowing down, decrease, increases,
terminal velocity, weight
18
Velocity-time graph for terminal velocity
Velocity




Time
19
Stopping a car
Too much alcohol
Tiredness
Too many drugs
Poor visibility
Wet roads
Icy roads
Tyres/brakes worn out
Driving too fast
20
Momentum
Any object that has both mass and velocity has
MOMENTUM. Momentum (symbol p) is simply given
by the formula

• What is the momentum of the following?
• A 1kg football travelling at 10ms-1
• A 1000kg Ford Capri travelling at 30ms-1
• A 20g pen being thrown across the room at 5ms-1
• A 70kg bungi-jumper falling at 40ms-1

21
Force and momentum
Newtons second law of motion says that the force
acting on an object is that objects rate of
change of momentum. In other words

• For example, David Beckham takes a free kick by
  kicking a stationary football with a force of
  40N. If the ball has a mass of 0.5kg and his
  foot is in contact with the ball for 0.1s
  calculate
• The change in momentum of the ball (its impulse),
• The speed the ball moves away with

22
Example questions

1. Ben likes playing golf. He strikes a golf ball
   with a force of 80N. If the ball has a mass of
   200g and the club is in contact with it for 0.2s
   calculate a) the change in momentum of the golf
   ball, b) its speed.
2. Nick thinks its funny to hit tennis balls at
   Tom. He strikes a serve with a force of 30N. If
   the ball has a mass of 250g and the racket is in
   contact with it for 0.15s calculate the balls
   change in momentum and its speed.
3. Dan takes a dropkick by kicking a 0.4kg rugby
   ball away at 10m/s. If his foot was in contact
   with the ball for 0.1 seconds calculate the force
   he applied to the ball.
4. Simon strikes a 200g golf ball away at 50m/s. If
   he applied a force of 50N calculate how long his
   club was in contact with the ball for.

23
Safety features
Lets use Newtons Second Law to explain how
airbags work

• Basically
• The change in momentum is the same with or
  without an airbag
• But having an airbag increases the time of the
  collision
• Therefore the force is reduced

24
Weight vs. Mass
Earths Gravitational Field Strength is 10N/kg.
In other words, a 1kg mass is pulled downwards by
a force of 10N.
Weight Mass x Gravitational Field Strength (in
N) (in kg) (in N/kg)

1. What is the weight on Earth of a book with mass
   2kg?
2. What is the weight on Earth of an apple with mass
   100g?
3. Dave weighs 700N. What is his mass?
4. On the moon the gravitational field strength is
   1.6N/kg. What will Dave weigh if he stands on
   the moon?

25
Stopping a car
Too much alcohol
Tiredness
Too many drugs
Poor visibility
Wet roads
Icy roads
Tyres/brakes worn out
Driving too fast
26
Work done
When any object is moved around work will need to
be done on it to get it to move (obviously).
We can work out the amount of work done in
moving an object using the formula
Work done Force x distance moved in J
in N in m
27
Example questions

1. Bori pushes a book 5m along the table with a
   force of 5N. He gets tired and decides to call
   it a day. How much work did he do?
2. Alicia lifts a laptop 2m into the air with a
   force of 10N. How much work does she do?
3. Martin does 200J of work by pushing a wheelbarrow
   with a force of 50N. How far did he push it?
4. Chris cuddles his cat and lifts it 1.5m in the
   air. If he did 75J of work how much force did he
   use?
5. Carl drives his car 1000m. If the engine was
   producing a driving force of 2000N how much work
   did the car do?

28
Elastic Potential Energy
Elastic potential energy is the energy stored in
a system when work is done to change its shape,
e.g
29
Kinetic energy
Any object that moves will have kinetic
energy. The amount of kinetic energy an object
has can be found using the formula
Kinetic energy ½ x mass x velocity squared in J
in kg in m/s
KE ½ mv2
30
Example questions

1. Nicole drives her car at a speed of 30m/s. If
   the combined mass of her and the car is 1000kg
   what is her kinetic energy?
2. Shanie rides her bike at a speed of 10m/s. If
   the combined mass of Shanie and her bike is 80kg
   what is her kinetic energy?
3. Dan is running and has a kinetic energy of 750J.
   If his mass is 60kg how fast is he running?
4. George is walking to town. If he has a kinetic
   energy of 150J and hes walking at a pace of 2m/s
   what is his mass?

31
Random questions

1. Sophie tries to run 100m in 12 seconds and
   succeeds. How fast did she run?
2. Tommy accelerates at a rate of 2m/s2 for 3
   seconds. If he started at 10m/s what was his
   final speed?
3. Charlie decides to lift his book up into the air.
   His book has a mass of 100g and he lifts it
   50cm. Calculate the work done.
4. Lewis accelerates from 0 to 10m/s in 5 seconds.
   If his mass is 70kg how much force did his legs
   apply?
5. Rachel rides 1km at a speed of 20m/s. How long
   did the journey take?
6. Claire thinks its funny to push James with a
   force of 120N. If James has a mass of 60kg
   calculate his acceleration.
7. Lauren slams on the brakes on her bike and her
   brakes do 20,000J of work. If the combined mass
   is 100kg what speed was she travelling at?
8. Tom has a mass of 75kg. If he accelerates from
   10 to 20m/s in 2s how much force did he apply?

32
Random questions

1. Georgina amuses herself by throwing things at
   Sarah. If she throws a ball with a speed of
   20m/s and the distance between her and Sarah is
   5m how long will it take to reach her?
2. Mr Richards throws calculators around the room
   with a force of 20N. If each calculator has a
   mass of 200g calculate the acceleration.
3. Sam has a mass of 70kg. What is his weight on
   Earth, where the gravitational field strength is
   10N/kg?
4. Zak does some work by pushing a box around with a
   force of 1N. He does 5J of work and decides to
   call it a day. How far did he push it?
5. On the moon Matt might weigh 112N. If the
   gravitational field strength on the moon is
   1.6N/kg what is his mass? What will he weigh on
   Earth?
6. Dan likes bird watching. He sees a bird fly 100m
   in 20s. How fast was it flying?
7. How much kinetic energy would Richard have if he
   travelled at a speed of 5m/s and has a mass of
   70kg?

33
Momentum
Any object that has both mass and velocity has
MOMENTUM. Momentum (symbol p) is simply given
by the formula

• What is the momentum of the following?
• A 1kg football travelling at 10ms-1
• A 1000kg Ford Capri travelling at 30ms-1
• A 20g pen being thrown across the room at 5ms-1
• A 70kg bungi-jumper falling at 40ms-1

34
Conservation of Momentum
In any collision or explosion momentum is
conserved (provided that there are no external
forces have an effect). Example question
Two cars are racing around the M25. Car A
collides with the back of car B and the cars
stick together. What speed do they move at after
the collision?
Mass 1000kg
Mass 800kg
Mass 1800kg
Momentum before momentum after so 1000 x
50 800 x 20 1800 x V V
36.7ms-1
35
Momentum in different directions
What happens if the bodies are moving in opposite
directions?
Momentum is a VECTOR quantity, so the momentum of
the second car is negative
Total momentum 1000 x 50 800 x 20 34000
kgms-1
Speed after collision 34000 kgms-1 / 1800
18.9ms-1
36
Another example
Consider the nuclear decay of Americium-241
If the new neptunium atom moves away at a speed
of 5x105 ms-1 what was the speed of the alpha
particle?
37
More questions

1. A white snooker ball moving at 5m/s strikes a red
   ball and pots it. Both balls have a mass of 1kg.
   If the white ball continued in the same
   direction at 2m/s what was the velocity of the
   red ball?
2. A car of mass 1000kg heading up the M1 at 50m/s
   collides with a stationary truck of mass 8000kg
   and sticks to it. What velocity does the
   wreckage move forward at?
3. A defender running away from a goalkeeper at 5m/s
   is hit in the back of his head by the goal kick.
   The ball stops dead and the players speed
   increases to 5.5m/s. If the ball had a mass of
   500g and the player had a mass of 70kg how fast
   was the ball moving?
4. A gun has a recoil speed of 2m/s when firing. If
   the gun has a mass of 2kg and the bullet has a
   mass of 10g what speed does the bullet come out
   at?

38
Force and momentum
Newtons second law of motion says that the force
acting on an object is that objects rate of
change of momentum. In other words

• For example, David Beckham takes a free kick by
  kicking a stationary football with a force of
  40N. If the ball has a mass of 0.5kg and his
  foot is in contact with the ball for 0.1s
  calculate
• The change in momentum of the ball (its impulse),
• The speed the ball moves away with

39
Example questions

1. Ben likes playing golf. He strikes a golf ball
   with a force of 80N. If the ball has a mass of
   200g and the club is in contact with it for 0.2s
   calculate a) the change in momentum of the golf
   ball, b) its speed.
2. Nick thinks its funny to hit tennis balls at
   Tom. He strikes a serve with a force of 30N. If
   the ball has a mass of 250g and the racket is in
   contact with it for 0.15s calculate the balls
   change in momentum and its speed.
3. Dan takes a dropkick by kicking a 0.4kg rugby
   ball away at 10m/s. If his foot was in contact
   with the ball for 0.1 seconds calculate the force
   he applied to the ball.
4. Simon strikes a 200g golf ball away at 50m/s. If
   he applied a force of 50N calculate how long his
   club was in contact with the ball for.

40
Safety features
Lets use Newtons Second Law to explain how
airbags work

• Basically
• The change in momentum is the same with or
  without an airbag
• But having an airbag increases the time of the
  collision
• Therefore the force is reduced

41
Static Electricity
Static electricity is when charge builds up on
an object and then stays static. How the
charge builds up depends on what materials are
used


-
-



-
-
-


-

-
-
42
Static Electricity
43
Van de Graaf generators
44
Uses of Static Smoke Precipitators
-
-
-
-
-
-
Positively charged grid



45
Uses and dangers of Static Electricity
Find out how static electricity is used in the
following
1) Photocopiers 2) Paint sprayer
Find out how static electricity is dangerous in
the following situations
1) Fuel pipes 2) Hospitals
46
Circuit Symbols
Variable resistor
Diode
Switch
Bulb
Ammeter
Voltmeter
LDR
Resistor
Cell
Fuse
Thermistor
Battery
47
Electric Current
Electric current is a flow of negatively charged
particles (i.e. electrons).
By definition, current is the rate of flow of
charge
48
Basic ideas
Words volts, amps, ohms, voltage, ammeter,
voltmeter
49
More basic ideas
If a battery is added the current will ________
because there is a greater _____ on the electrons
If a bulb is added the current will _______
because there is greater ________ in the circuit
50
Current in a series circuit
In other words, the current in a series circuit
is THE SAME at any point
51
Current in a parallel circuit
A PARALLEL circuit is one where the current has a
choice of routes
52
Current in a parallel circuit
If the current here is 6 amps
53
Some example questions
54
Voltage in a series circuit
2V
55
Voltage in a series circuit
4V
56
Voltage in a parallel circuit
4V
4V
57
Summary
In a SERIES circuit Current is THE SAME at any
point Voltage SPLITS UP over each component
In a PARALLEL circuit Current SPLITS UP down
each strand Voltage is THE SAME across
eachstrand
58
An example question
6V
A3
3A
A1
V1
A2
V2
V3
59
Another example question
10V
A3
3A
A1
V1
A2
V2
V3
60
Resistance
The resistance of a component can be calculated
using Ohms Law
61
An example question

1. What is the resistance across this bulb?
2. Assuming all the bulbs are the same what is the
   total resistance in this circuit?

62
More examples
6V
12V
What is the resistance of these bulbs?
63
Resistance
Resistance is anything that opposes an electric
current.

• What is the resistance of the following
• A bulb with a voltage of 3V and a current of 1A.
• A resistor with a voltage of 12V and a current of
  3A
• A diode with a voltage of 240V and a current of
  40A
• A thermistor with a current of 0.5A and a voltage
  of 10V

64
Resistors, bulbs and diodes
65
Current-Voltage Graphs
Voltage on powerpack/V Current/A Voltage/V
12 10 0 -10 -12
66
Current-voltage graphs
3. Diode
1. Resistor
A diode only lets current go in one direction
it has very high resistance in the other direction
Current increases in proportion to voltage
2. Bulb
As voltage increases the bulb gets hotter and
resistance increases
67
LDRs and Thermistors
68
Two simple components
2) Thermistor resistance DECREASES when
temperature INCREASES
1) Light dependant resistor resistance
DECREASES when light intensity INCREASES
69
Wiring a plug
Earth wire
Live wire
Fuse
Neutral wire
Cable grip
Insulation
The live wire of a plug alternates between
positive and negative potential relative to the
Earth
The neutral wire of a plug stays at a potential
close to zero relative to the Earth
70
DC and AC
V
DC stands for Direct Current the current only
flows in one direction
Time
1/50th s
AC stands for Alternating Current the current
changes direction 50 times every second
(frequency 50Hz)
230V
T
V
71
Using an oscilloscope
Q. What is the voltage and frequency of this
supply?
72
Fuses
Fuses are _______ devices. If there is a fault
in an appliance which causes the ____ and neutral
(or earth) wire to cross then a ______ current
will flow through the _____ and cause it to
_____. This will break the _______ and protect
the appliance and user from further _____.
Words large, harm, safety, melt, live, circuit,
fuse
73
Power and fuses
Power is the rate of doing work. The amount of
power being used in an electrical circuit is
given by
Power voltage x current in W in V
in A
Using this equation we can work out the fuse
rating for any appliance. For example, a 3kW
(3000W) fire plugged into a 240V supply would
need a current of _______ A, so a _______ amp
fuse would be used (fuse values are usually 3, 5
or 13A).
74
Power and fuses
Copy and complete the following table
Appliance Power rating (W) Voltage (V) Current needed (A) Fuse needed (3, 5 or 13A)
Toaster 960 240
Fire 2000 240
Hairdryer 300 240
Hoover 1000 240
Computer 100 240
Stereo 80 240
75
Energy and Power
The POWER RATING of an appliance is simply how
much energy it uses every second. In other
words, 1 Watt 1 Joule per second
E Energy (in joules) P Power (in watts) T
Time (in seconds)
76
Some example questions

1. What is the power rating of a light bulb that
   transfers 120 joules of energy in 2 seconds?
2. What is the power of an electric fire that
   transfers 10,000J of energy in 5 seconds?
3. Farhun runs up the stairs in 5 seconds. If he
   transfers 1,000,000J of energy in this time what
   is his power rating?
4. How much energy does a 150W light bulb transfer
   in a) one second, b) one minute?
5. Shauns brain needs energy supplied to it at a
   rate of 40W. How much energy does it need during
   a physics lesson?
6. Damiens brain, being more intelligent, only
   needs energy at a rate of about 20W. How much
   energy would his brain use in a normal day?

77
Earth wires
Earth wires are always used if an appliance has a
_____ case. If there is a _____ in the
appliance, causing the live wire to ______ the
case, the current _______ down the earth wire
and the ______ blows.
Words fuse, fault, metal, surges, touch
78
Charge (Q)
As we said, electricity is when electrons move
around a circuit and carry energy with them.
Each electron has a negative CHARGE. Charge is
measured in Coulombs (C). We can work out how
much charge flows in a circuit using the equation
Charge current x time (in C) (in A)
(in s)
79
Example questions
Charge (C) Current (A) Time (s)
5 2
0.4 1
20 0.5
50 250
3 60

1. A circuit is switched on for 30s with a current
   of 3A. How much charge flowed?
2. During electrolysis 6A was passed through some
   copper chloride and a charge of 1200C flowed.
   How long was the experiment on for?
3. A bed lamp is switched on for 10 minutes. It
   works on a current of 0.5A. How much charge
   flowed?

80
Energy and charge
The amount of energy that flows in a circuit will
depend on the amount of charge carried by the
electrons and the voltage pushing the charge
around
Energy transferred charge x voltage (in
J) (in C) (in V)
81
Example questions

1. In a radio circuit a voltage of 6V is applied and
   a charge of 100C flows. How much energy has been
   transferred?
2. In this circuit the radio drew a current of 0.5A.
   How long was it on for?
3. A motor operates at 6V and draws a current of 3A.
   The motor is used for 5 minutes. Calculate a)
   The motors resistance, b) the charge flowing
   through it, c) the energy supplied to it
4. A lamp is attached to a 12V circuit and a charge
   of 1200C flows through it. If the lamp is on for
   10 minutes calculate a) the current, b) the
   resistance, c) the energy supplied to the bulb.

82
Random questions

1. A battery has a voltage of 12V and it puts a
   current of 3A through a bulb. What is the bulbs
   resistance?
2. Another bulb transfers 120C of charge in 2
   minutes. What was the current through it?
3. A powerpack transfers 2,000J to a motor. If the
   motor ran on a voltage of 50V how much charge was
   transferred?
4. A hairdryer runs on a 50Hz power supply. If it
   has a power rating of 200W what fuse should it
   have?
5. An electric fire transfers 3MJ of energy. If it
   has a power rating of 2KW calculate how long it
   was on for, the current it ran on (assuming it
   was connected to the mains supply) and the amount
   of charge it transferred.

83
Structure of the atom
A hundred years ago people thought that the atom
looked like a plum pudding a sphere of
positive charge with negatively charged electrons
spread through it
Ernest Rutherford, British scientist
I did an experiment (with my colleagues Geiger
and Marsden) that proved this idea was wrong. I
called it the Scattering Experiment
84
The Rutherford Scattering Experiment
Alpha particles (positive charge, part of helium
atom)
Thin gold foil
Most particles passed through, 1/8000 were
deflected by more than 900
Conclusion atom is made up of a small,
positively charged nucleus surrounded by
electrons orbiting in a cloud.
85
The structure of the atom
86
The structure of the atom
Particle Relative Mass Relative Charge
Proton 1 1
Neutron 1 0
Electron 0 -1
87
Isotopes
An isotope is an atom with a different number of
neutrons
A radioisotope is simply an isotope that is
radioactive e.g. carbon 14, which is used in
carbon dating.
88
Background Radiation
89
Types of radiation
1) Alpha (?) an atom decays into a new atom
and emits an alpha particle (2 protons and 2
______ the nucleus of a ______ atom)
Unstable nucleus
New nucleus
Alpha particle
2) Beta (?) an atom decays into a new atom by
changing a neutron into a _______ and electron.
The fast moving, high energy electron is called a
_____ particle.
Beta particle
Unstable nucleus
3) Gamma after ? or ? decay surplus ______ is
sometimes emitted. This is called gamma
radiation and has a very high ______ with short
wavelength. The atom is not changed.
Words frequency, proton, energy, neutrons,
helium, beta
Unstable nucleus
New nucleus
Gamma radiation
90
Nuclear fission
New nuclei (e.g. barium and krypton)
91
Chain reactions
Each fission reaction releases neutrons that are
used in further reactions.
92
Nuclear Fusion in stars
Proton
Neutron
93
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