# Physics Key Points

The key points for every single topic in the AQA Additional Science course for Chemistry. Presented in a nice and colourful way!

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Physics Key Points
Motion
Distance-time graphs
The gradient of the line on a distance-time graph represents an object's speed.
The steeper the line on a distance-time graph, the greater the speed it represents.
Speed (m/s)= distance
travelled (m)
time taken (s)
Velocity and acceleration
Velocity is speed in a given direction.
Acceleration is the change of velocity per second.
Acceleration (a) = final velocity
(v)-initial velocity (u)
time taken (t)
If the line on a velocity-time graph is horizontal, the acceleration is zero.
The gradient of a velocity-time graph represents acceleration.
The area under the line on a velocity-time graph is the distance travelled.
Using graphs
The speed of an object is given by the gradient of the line on its distance-time graph.
The acceleration of an object is given by the gradient of the line on its velocity-time
graph.
The distance travelled by an object is given by the area under the line on its
velocity-time graph.
Forces
Forces between objects
A force can change the shape of an object or change its motion or state of rest.
The unit of force is the newton (N).
When two objects interact they always exert equal and opposite forces on each
other.
Resultant force
The resultant force is a single force that has the same effect as all the forces acting
on an object.
If an object is accelerating there must be a resultant force acting on it.

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Force and acceleration
The bigger the resultant force on an object, the greater its acceleration.
The greater the mass of an object, the smaller its acceleration for a given force.
Resultant force (f ) = mass (m) x acceleration (a)
Friction and air resistance oppose the driving force of a car.
The stopping distance of a car depends on the thinking distance and the braking
distance.
Falling objects
The weight of an object is the force of gravity on it.…read more

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Gravitational potential energy
The gravitational potential energy of an object depends on its weight and how far it
moves vertically.
Change in G.P .E (E) = mass (m) x gravitational filed strength (g) x change in height (h)
Kinetic energy
The kinetic energy of a moving object depends on its mass and speed.
K inetic energy (Ek) = 1/2x mass (m) x velocity² (v²)
Elastic potential energy is the energy stored in an elastic object when work is done

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Current electricity
Electrical charges
Certain insulating materials become charged when rubbed together.
Electrons are transferred when objects become charged.
Like charges repel; unlike charges attract.
Electric circuits
Every component has its own agreed symbol.…read more

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Mains electricity
Alternating current
Direct current is in one direction only. Alternating current repeatedly reverses its
direction.
The peak voltage of an alternating potential difference is the maximum voltage
measured from zero volts.
A mains circuit has a live wire that is alternately positive and negative every cycle and
a neutral wire at 0 volts.
f requency (f ) = time1 (T )
Cables and plugs
Sockets and plugs are made of stiff plastic materials, which enclose the electrical

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Electrical issues
Electrical faults are dangerous because they can cause electric shocks and fires.
Never touch a mains appliance (or plug or socket) with wet hands. Never touch a bare
wire or a terminal at a potential of more than 30V.
Check cables, plugs and sockets for damage regularly.
A radioactive substance contains unstable nuclei that become stable by emitting
There are three main types of radiation from radioactive substances- alpha, beta and

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The activity of a radioactive source is the number of nuclei that decay per second.
The number of atoms of a radioactive isotope and the activity both decrease by half
every half-life.
The use we can make of a radioactive isotope depends on its half-life, and the type of

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The life history of a star
A protostar is a gas and dust cloud in space that can go on to form a star.
Low mass star: protostar main sequence star red giant white drawf black
drawf
High mass star: protostar main sequence star red supergiant supernova
black hole if sufficient mass.
The Sun will eventually become a black drwaf.
A supernova is the explosion of a supergiant after it collapses.…read more