Module 1: Kinematics

1.1 Motion in a Straight Line

• Vector = a quantity having both direction and magnitude

• Scalar = a quantity having both

1.2 Motion on a Plane

Module 2: Dynamics

2.1 Forces

• Force = an influence that acts to change the motion of a body or to impose an elastic strain on it

• Contact forces = applied friction, air resistance, fluid drag, tension, normal reaction force, buoyant force

• Non-contact forces = gravitational, electromagnetic, electrostatic, strong nuclear, weak nuclear

• Gravitational force = a force of attraction that exists between any pair of objects that have mass

• Force exerted on an object due to the pull of gravitational attraction is called weight (W)

• The magnitude of the weight of an object is directly proportional to its mass

• Weight changes dependent on where you are; mass doesn’t * Weight = Newtons (N)

• Mass = m (kg)

• Gravitational field strength = weight/mass N Kg^-1 or m s^-2 (as its also acceleration due to gravity)

• Direction for the weight vector must be stated to describe weight fully - ‘towards the centre of the ’

• Upwards forces or support forces = normal reaction force

• Normal reaction force = acts at right angles to the surface and is called a reaction force as it is only acting in response to the force that a body is applying to the floor

• Normal reaction force = R and is equal in magnitude to the sum of the forces exerted perpendicularly to a surface

2.2 Forces, Acceleration and Energy

• Friction = a force that resists the motion of one surface across another, its direction is always opposite to the direction of the motion of the object

• Frictional force = acts parallel to a surface

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• Static friction = the frictional force that must be overcome as you first start to push one surface across another

• The size of the static force is equal to the force applied to the surfaces up to a maximum value called the limiting friction

• When the applied force is large enough to overcome the maximum value the surfaces will start to move

• Sliding friction = takes effect once the static friction has been overcome by the applied force and the materials are moving past each other * Sliding friction is weaker than static friction in magnitude

• The frictional force is directly proportional to the normal reaction force and the coefficient of friction

• Frictional force (Ff) = coefficient of friction (mu) x normal reaction force (R)

• The coefficient of friction has no units as it is the ratio of friction force to the normal reaction force and is a measure of how easily two surfaces move across each other * The vector sum of all the forces (sigmaF) acting on an object = net force (Fnet)

• Equilibrium = a state of balance resulting from the application of two or more forces that produce a zero net force

• Newton’s first law = a body in motion will stay in motion, or a body at rest will stay at rest, unless acted on by an unbalanced, external force

• Newton’s second law = the acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object (F=ma)

• v = u + at * s = ut + 1/2at^2 * v^2 = u^2 +2as

• Newton’s third law = whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first object

• Energy = capacity of a physical system to do work

2.3 Momentum, Energy and Simple Systems

Module 3: Waves and Thermodynamics

3.1 Wave Properties

• Mechanical waves = require a medium in order to transport their energy from one location to another

• Mechanical waves aren’t capable of transmitting their energy through a vacuum

• Once a mechanical wave has passed through the particles they will return to their original position

• Mechanical waves transfer energy without any net movement of particles

• Electromagnetic waves = don’t require a medium to be transmitted

• Sound waves = mechanical

• Light waves = electromagnetic

• Transverse mechanical waves = the vibration of the particles is at right angles to the direction of energy travel

• eg. ripples on the surface of a pool when a rock is dropped into it

• Longitudinal waves = the vibration of the particles is parallel to the direction of energy travel

• Compressions and rarefactions

• eg. slinky

• Periodic waves = are disturbances that repeat themselves at regular intervals

• Period of a periodic wave = the time taken for one cycle of an oscillating particle or the time it takes to for one complete wave to pass a given point

• Period measured in seconds and represented by a T

3.2 Wave Behaviour

3.3 Sound Waves

3.4 Ray Model of Light

3.5 Thermodynamics

Module 2: Electricity and Magnetism

4.1 Electrostatics

• The positive charge on a proton is equal in magnitude to the negative charge on an electron

• Two positive charges = repel

• Two negative charges = repel

• A positive and a negative charge = attract

• Like charges repel; unlike charges attract

• SI unit of charge = coulomb (C)

• Charge of one coulomb = total charge on 6.242x10^18 electrons or protons

• Charge of one electron = -1.602x10^-19 C

• Charge of one proton = +1.602x10^-19 C

• Coulomb is a very large charge, two 1C charges placed 1 metre apart would exert forces of approx. 1010N on each other

• A charge on a body due to an excess or deficiency of electrons = electrostatic charge

• A conductor = material that contains charge carries ( charged particles free to move through the material)

• eg. metals = charge carries are electrons

• An insulator = material that contains no available charge carriers

• If an insulator is given an electrostatic charge at a particular area on the insulator, the charge will remain at that area

• There are two possibilities if a conductor is given an electrostatic charge

• 1. if the conductor is insulated (not earthed) electrons will move within the conductor so that the electrostatic charge is as spread out as possible. The electrostatic charge will be distributed on the surface of the conductor

• 2. if the conductor is earthed electrons will move to or from the Earth to neutralise the conductor

• Methods of charging = charging by friction, charging by contact, charging by induction

• Charging by friction = two bodies of different materials are rubbed together a small number of electrons will be transferred from one body to another

• eg. perspex and silk → perspex = positively charged, silk = negatively charged

• eg. ebonite and wool → ebonite = negatively charged, wool = positively charged

• Charging by contact = if a charged conductor is brought into contact with an uncharged conductor, the charge will be shared between the two conductors

• Charging by induction = charged body brought near an insulated, uncharged conductor causes either protons or electrons to be attracted to the body creating negative and positively charged ends of the conductor

• Charges on conductor = induced charges

• This process is induction

• Induced charges can also be produced if a charged body is brought near an insulator = positively charged body will attract the electrons and repel the nuclei in each atom of the insulator

• Conservation of charge = when two previously neutral bodies are charged by friction, the amount of positive charge produced on one body is equal to the amount of negative charge produced on the other body

• Any charged object is surrounded by an electric field

• Any charge brought into the field will experience a force (either an attraction or a repulsion)

• The direction of the electric field at a point is defined as being equal to the direction of the force experienced by a positive test charge placed in the field at that point

• The electric field is directed from positive charges towards negative charges or is directed from potential to low potential

• A positive charge will experience a force in the direction of the field

• A negative charge will experience a force in the opposite direction to the field

• Electric field vectors = represented by vector arrows, direction of the arrow is from positive to negative or from high to low potential to represent the direction of the field, smaller distances between the electric field lines represent a stronger electric field * When a positive and a negative charge are separated by a short distance, the electric field around them is called a dipole field

4.2 Electric Currents and Models

4.3 Magnetism