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Physics Revision Sheet 2

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Physics Revision Sheet 2
P2 REVISION – CHAPTER 1 – Motion
Distance-time Graphs
Using Graphs
The gradient of the line on a distance-time graph represents _________.
The ______________ the gradient, the greater the speed.
If an object is stationary, the line on a distance-time graph is
______________.
If an object is moving at a constant speed, the line on a distance-time
graph is a straight line that slopes _____________.
Velocity & Acceleration
Velocity-time graphs
The gradient of the line on a
velocity-time graph represents
______________.
The steeper the
____________, the greater
the acceleration.
What does a horizontal line
show on a velocity-time graph?
What area on a velocity-time
graph shows the distance?
If the value calculated for acceleration is
negative, the body is decelerating – slowing
down. A deceleration is the same as a
negative acceleration.
Calculate the gradient of the line on a distance-time
graph to give you the speed of an object.
Calculate the gradient of
the line on a velocity-time
graph to give you the
acceleration of an object.
KEY WORDS:
Velocity
Acceleration
Deceleration
Speed
ASSESSMENT:
P2 REVISION – CHAPTER 2 – Forces
Forces between objects.
Resultant Force
The resultant force is a single force that
has the same effect as all the forces acting
on an object.
Forces are measured in
newtons, N.
What is the rule with regard to
forces?
If an object is accelerating there must be a
resultant force acting on it.
If an object is accelerating what 3 things
can it be doing?
On the Road
If a vehicle is travelling at a steady speed, the resultant force on
it is __________. The driving forces are equal and opposite to
the frictional forces.
Stopping distance
Distance travelled during the
thinking distance, plus the
distance it travels under the
braking distance
Thinking distance
Is increased if the driver is tired
or under the influence of
_____________ or
__________.
Force and Acceleration
What always causes an acceleration?
The bigger the resultant force on an object, the greater its
___________________.
Braking distance
F=mxa
F is the resultant force in newtons, N.
m is the mass in kilograms, kg
a is the acceleration in m/s²
Acceleration is a change in velocity. An object can accelerate by changing its
________________ even if it is going at a ______________ ____________.
Therefore a ___________________ ______________ is needed to make an
object change __________________.
Can be increased by:
Poorly maintained roads
Bad weather conditions.
Condition of the car: eg:
Worn ____________
Worn ____________
Reaction time depends on the ____________.
Braking distance depends on the ___________,
___________ _____________ and the condition of
the vehicle.
KEY WORDS:
Force
Newton
Mass
ASSESSMENT:
P2 REVISION – CHAPTER 2 – Forces continued.
Falling Objects
Stretching & Squashing
What does elastic mean?
The force of gravity is called ___________
An object acted on only by gravity will
accelerate at about ___________.
F=mxa
Where:
F is the resultant force in newtons, N.
m is the mass in kilograms, kg
a is the acceleration in m/s²
Becomes:
W=mxg
Where:
W is the weight in newtons, N
m is the mass in kilograms, kg
g is the acceleration due to gravity in m/s²
If an object falls through a fluid the fluid
exerts a __________ force on the object.
Faster the object falls, the bigger the drag
force becomes until it becomes equal to
the weight of the object.
Resultant force will then be ___________.
This is called ________________
_______________.
DON’T FORGET:
Mass is the amount of matter in an object.
Weight is the force of gravity acting on it.
Force and Speed Issues
Reduces the speed of a vehicle reduces the amount of
what?
What is this called?
The extension of a spring is
DIRECTLY PROPORTIONAL to the
force applied to it, provided the
limit of proportionality is not
exceeded.
How do we know that it is directly
proportional?
Reducing air resistance, making a vehicle more
_________________ also improves fuel economy.
Speed cameras are used to discourage motorists from doing
what?
In pairs they can be used to calculate __________________
speed.
What happens if you are caught speeding?
When does skidding happen?
Extension is the difference
between the length of the spring
and its ____________
_________.
Hooke’s Law
Equation: F = k x e
Where
F is the force applied in newtons, N
k is the spring constant of the
spring in newtons per metre, N/m
e is the extension in metres, m
What is the spring constant of a
spring?
What happens when you skid?
_________ ___________ surfaces are used to reduce or
prevent skidding.
How do these surface work?
Where are they used?
KEY WORDS:
Gravitational
Drag force
Terminal velocity
Weight
Elastic
Proportionality
ASSESSMENT:
P2 REVISION – CHAPTER 3 – Work, Energy & Momentum
Energy & Work
Explosions
Work is done on an object when a force makes the object move.
Energy transferred = work _______
What is the unit for both work and energy?
W=Fxd
Where:
W is the work done in joules, J
F is the force in newtons, N
d is the distance moved in the direction of the force in metres, m
Work done to overcome _____________ is transferred as energy that heats the
objects that rub together and the surroundings.
Gravitational Potential Energy
Momentum has both size and direction.
One direction must be ________________, therefore
momentum in the opposite direction is negative.
In an explosion the objects will move apart with
_______________ and ______________________
momentum. One being positive the other ______________.
So the total momentum after the explosion is ____________.
Kinetic Energy
The object will move apart with different speeds if they have
_____________ _______________.
KEY WORDS:
Work
Friction
Kinetic energy
Elastic potential energy
ASSESSMENT:
P2 REVISION – CHAPTER 3 –Work, Energy & Momentum cont.
Impact Forces
Car Safety
When vehicles collide the force of the impact depends on what 3
things?
When two vehicles collide they exert ______________ and
__________________ forces on each other, also their total
_______________________ is unchanged.
Cars today have several different safety features built into them, to reduce
the forces on the occupants of the car in a collision.
How do side impact bars, seat belts, air bags and crumple zones help with
safety?
What is impact time?
Questions
What can we use to find out the speed of a car before an
impact?
What is the unit of momentum?
Where do you have crumple zones on a car and why?
KEY WORDS:
Impact time
Crumple zone
ASSESSMENT:
P2 REVISION – CHAPTER 4 – Current Electricity
Electrical Charges
If you rub two electrically
insulating materials are rubbed
together, __________________
are rubbed off one material and
deposited on the other.
Objects that have opposite electric
charges ______________ each
other, if they have the same
electric charge they___________.
Electric Circuits
Electric symbols
I is the current in amperes, A
Q is the charge in coulombs, C
t is the time in seconds, s.
Every component has an agreed circuit
symbol.
Make sure you can recognise and draw
them!
Resistance
Current is measured with an ammeter. Where are ammeters placed in relation to
the component?
What is the unit of current?
The potential difference(pd) across a component is measured with a voltmeter.
These are always placed in parallel with the component. What is the unit of potential
difference?
V is ?
W is ?
Q is ?
Don’t forget units!
R is ?
V is ?
I is ?
Don’t forget units!
Ohm’s law: states that the current through a resistor at constant temperature is
directly proportional to the potential difference across the resistor.
KEY WORDS:
Insulating
Electron
Attract
Repel
Resistance
Series
ASSESSMENT:
P2 REVISION – CHAPTER 4 – Current Electricity Cont.
Series Circuits
Current-Potential Difference Graphs
A current-potential difference
graph for a resistor.
How are the components connected in a series circuit?
What happens if there is a break in the circuit?
Is the current the same or different through each component?
If you add together the potential difference what does it give you?
The resistance of the individual
components add up to give the
total resistance of the circuit.
A current-potential difference
graph for a filament bulb, line is
a curve so the current is not
directly proportional to the
__________________
___________________.
The current in a diode flows
in one direction only, in the
reverse direction the diode
has a very high resistance so
the current will be what?
Parallel Circuits
How are the components connected in a series circuit?
What happens if there is a break in the circuit?
Is the pd across each component the same or different?
The bigger the resistance of a component, the ______________ the current through it.
Use this equation to work out the
current through a component in a
parallel circuit.
Thermistor: Resistance _______________ if its temperature
increases.
LDR: resistance decreases if the light intensity on it ___________.
KEY WORDS:
Diode
Filament bulb
Resistor
Thermistor
ASSESSMENT:
P2 REVISION – CHAPTER 5 – Mains Electricity
Alternating Current
Direct current is supplied by cells and
batteries and passes round the circuit
in one direction.
Alternating current is from the mains,
how does it travel?
Frequency of am ac supply can be
worked out from an oscilliscope trace
using the equation:
Cables & Plugs
Fuses
How does a fuse work?
Where is a fuse fitted in a circuit?
Electrical Energy & Charge
An electric current is the flow of what?
What is the equation that relates to charge, current and time?
When charge flows through a resistor, what makes it hot?
How does a circuit breaker work?
What can you use this equation for?
Electrical Power & Potential
Difference
Power can be calculated using the
above equation.
Electrical Issues
Electrical faults are dangerous what two things can they cause?
Why must you check cables, plugs and sockets for damage
regularly?
What must you not touch with wet hands?
Why are the pins of a plug made of
brass?
What does the earth wire earth?
Why are some cables thicker than
others?
Using the current and the pd and the
equation above enables us to
calculate the power of an appliance.
To work out the correct rating in
amperes for a fuse rearrange the
above equation, what would the
equation now be?
Why are filament bulbs very inefficient?
KEY WORDS:
Current
Frequency
Oscilloscope
Circuit breaker
ASSESSMENT:
P2 REVISION – CHAPTER 6 – Radioactivity
Observing Nuclear Radiation
Nuclear Reactions
Change in the Nucleus
An atom has a small central _________________, which contains the ____________
and _________________, this is then surrounded by_______________________.
The nuclei of radioactive substances are unstable, to become stable they go through
a process called radioactive decay.
The 3 types of radiation emitted are:
Particle emitted
α decay
β decay
Where does background radiation come from?
Relative Mass
Remember: Radioactive decay is random we cannot predict or influence when it
happens!
Relative Charge
Proton
Neutron
Electron
Discovery of the Nucleus
What is an atom called if it loses or gains electrons?
Scientists originally called the model of the atom the
‘plum pudding’.
Rutherford, Geiger and Marsden then did an alpha
particle scattering experiment, they fired alpha particles
at thin gold foil.
Most passed straight through the foil, what does this
mean?
Some of the alpha particles are deflected through small angles, what does this mean?
A few rebound through large angles what does this mean?
What is an isotope?
When a nucleus emits an alpha particle the atomic number
goes down by _____ and the mass number goes down by ___.
When a nucleus emits a beta particle the atomic number goes
up by ___ and the mass number stays the same.
Is there any change when a nuclear emits gamma radiation?
KEY WORDS:
Ion
Isotope
Nucleus
Proton
Electron
Radiation
ASSESSMENT:
P1 REVISION – CHAPTER 6 – Radioactivity cont.
Half-Life
Alpha, beta & gamma radiation
Remember
what stops
each type of
radiation.
What is the half-life of a radioactive isotope?
The number of atoms of a radioactive isotope
and the activity both decrease by __________
every half life.
Deflected by?
Alpha
Radioactivity at Work
Where used and length of half-life
Electric & magnetic fields
Not as ionising as
alpha particles
Beta
Gamma
How ionising?
Deflected by neither
electric or magnetic fields.
Alpha
Beta
Tracers in medicine. Half-life of a few hours so that patient is not
exposed to unnecessary radioactivity.
Radioactive Dating: What is this used for? What do we need to do it?
Ionisation is when nuclear radiation travels through a
material, colliding with the atoms within it. This then
knocks electrons off, creating ions.
KEY WORDS:
Ionisation
Half-life
Tracer
Radioactive dating
ASSESSMENT:
P1 REVISION – CHAPTER 7 – Energy From the Nucleus
Nuclear Fission
The Early Universe
Nuclear fission is the splitting of a nucleus into two approximately equal
fragments and the release of two or three neutrons.
What two fissionable isotopes are most commonly used in nuclear reactors?
How and when do many scientists think the universe was
created?
What pulled the gas and dust together to form stars?
When does a chain reaction occur?
What are very large groups of stars called?
Nuclear Fusion
Nuclear Issues
Nuclear fusion is the process of forcing
two nuclei close enough together so
they form a single larger nucleus.
What is a major source of background
radiation?
What is released when this happens?
Name two other sources of
background radiation.
Where does nuclear fusion take place?
How is nuclear waste stored?
Why must it be stored securely?
KEY WORDS:
Star
Nuclear fusion
Chain reaction
Nuclear fission
ASSESSMENT:
P1 REVISION – CHAPTER 7 – Energy From the Nucleus cont
How the chemical elements formed
Life History of a Star
Protostar: Gas and dust cloud in space that can go on to form a star.
Gas, rocks and dust
Low mass star:
Protostar
main sequence star
Black dwarf
red giant
High mass star:
Protostar
Supernova
main sequence star
red supergiant
black hole if sufficient mass.
white dwarf
The sun forms at the centre of a spinning cloud of dust, gas and
rock.
The sun’s energy evaporates ice and drives gas away from the
inner solar system, leaving rocks behind.
What will the sun eventually become?
What is a supernova?
The rocky planets form near the Sun and the gas giant planets
form further away. The minor planet Pluto orbits the Sun beyond
the giant planets.
Elements as heavy as iron are formed inside stars as a result of
nuclear _______________.
Elements heavier than iron are formed in supernovas, along with
lighter elements.
What were the sun and the rest of the solar system formed from?
KEY WORDS:
Pro star
Supernova
Neutron star
ASSESSMENT:
Fly UP