# physics unit 2 revision notes higher tier

physics unit 2 revision notes higher tier

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AQA GCSE Biology ­ Unit 2 summary notes
P2 Physics
Speed and Velocity
A time-distance graph plots distance travelled against the time taken
A slope on a time-distance graph represents speed, the steeper the slope the greater
the speed
o Speed = distance ÷ time
o Distance = speed x time
o Time = distance ÷ speed
Speed is measured in meters per second (m/s)
Velocity is a speed but with a given direction
This means that if a moving object changes direction then its velocity will change even
if its speed says the same
If the velocity we say the object is accelerating or decelerating
o Acceleration = change in velocity ÷ time taken for the change
Acceleration is measured in meters per second per second (m/s²)
A velocity-time graph plots the velocity against the time taken
The slope on a velocity time graph represents the acceleration or deceleration
The steeper the slope the greater the acceleration or deceleration
The area under the graph represents the distance travelled
We use the gradient of the line to work out the speed of an object, for example if the
graph shows it has moved 10 meters in 2 seconds then its speed is 5m/s
Speeding up and slowing down
We measure force in newtons (N)
Objects always exert equal and opposite forces on each other, these are often referred
to as action and reaction forces
Resultant force is where one single force will have the same effect than all the other
forces put together
When the resulting force is zero it means the object is stationary or is travelling at a
constant speed
If the resulting force is not equal to zero then it means the object is accelerating in the
direction of the resulting force
A resulting force always causes an acceleration, without acceleration the resulting
force must be zero
o Resulting force = mass x acceleration
The greater the resulting force the greater the acceleration
A vehicle travelling at a constant pace has a resulting force of zero which means the all
the driving forces are equal
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AQA GCSE Biology ­ Unit 2 summary notes
The stopping distance is of a vehicle is the distance travelled by the object during the
thinking distance and the breaking distance
The thinking distance is increased if the driver is under the influence of alcohol or
drugs and the braking distance is increased if the road is wet or the brakes are worn
When an object is falling freely, the resulting force acting on it is gravity
o Weight = mass x acceleration due to gravity…read more

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AQA GCSE Biology ­ Unit 2 summary notes
When a force acts on a moving object its momentum changes
Force = change in momentum ÷ time taken
If you increase the time taken then the force exerted decreases e.g.…read more

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AQA GCSE Biology ­ Unit 2 summary notes
Static electricity can be dangerous as well as being very useful
The filler pipes on road tankers that are used to pump fuel into storage tanks are
earthed to prevent them becoming charged because a spark could cause an explosion
Another way to prevent the dangers of electrostatics is by using antistatic materials
Current Electricity (look at pictures for circuit symbols)
A cell is necessary to push electrons around a complete circuit
A battery consists of two…read more

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AQA GCSE Biology ­ Unit 2 summary notes
o Power = current x potential difference
The potential difference of the mains supply is 230 volts so the equation above can be
used to work out what fuse is needed
In a resistor the electrical energy is transferred to heat, the amount of energy that's
transformed can be worked out using the equation below
o Energy = potential difference x charge
A coulomb (C) is the amount of electric charge transported in one second through a…read more

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AQA GCSE Biology ­ Unit 2 summary notes
In a parallel circuit the current varies with resistance between each component
Mains electricity
Cells (and battery's) supply a current which only flows in one direction, this is called a
direct current or DC, however if the current from the mains supply passes in one
direction then reverses and passes in the other direction it is called an alternating
current or AC
The frequency of the UK mains electricity is 50Hertz (Hz), this means it is alternating…read more

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AQA GCSE Biology ­ Unit 2 summary notes
Atoms of the same element can also have a different number of neutrons in which
case it is an isotope, only the neutron number and the electron number can change or
it becomes a different element
An alpha particle consists of two protons and two neutrons, this means that when a
nucleus emits an alpha particle, the atomic number decreases by 2 and the mass

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AQA GCSE Biology ­ Unit 2 summary notes
The neutrons go on to produce further reactions creating a chain reaction, in a nuclear
reactor the process of fission is controlled so one fission neutron per fission on
average foes on to produce further fission
Nuclear fusion is the process of two atomic nuclei joining to form one single, larger
nucleus, during this process energy is released (this is the process in which energy is
released as stars)
The problems with nuclear fusion are the nuclei…read more