Unit 4 definitions

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Momentum
Mass x velocity
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Principle of conservation of momentum
Momentum is conserved in all interactions where no external force acts
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Newton’s 2nd law of motion
The rate of change of momentum of a body is directly proportional to the resultant force acting on it
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Elastic collision
Total kinetic energy before the collision = the total kinetic energy after the collision
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Inelastic collision
Total kinetic energy before the collision is greater than the total kinetic energy after the collision (some kinetic energy is transferred into other forms during the collision)
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Magnetic field
Region of space around a magnet where it exerts magnetic forces
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Catapult field
The magnetic field of the magnet exerts a force on the magnetic field of the current carrying conductor. The direction of the force is given by FLHR
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Magnetic flux
Magnetic flux density x area of coil
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Magnetic flux linkage
Magnetic flux through coil x number of turns of the coil
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Faraday’s law
the induced e.m.f. across the ends of a conductor is directly proportional to the rate of change of magnetic flux the conductor experiences
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Lenz’s law
The direction of the induced e.m.f. is such that it tends to oppose the flux change causing it, and does oppose it if an induced current flows
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Eddy current
Current induced in the soft iron core of a transformer due to the changing magnetic flux in the core
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Capacitance
Charge stored on the plates of a capacitor when a p.d. of 1 volt is applied. (charge / p.d.)
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Time constant
Time taken for the charge on a capacitor to drop to 1/e of its original value (R x C)
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Exponential
A change where the property (charge) changes by a constant ratio in a fixed time interval
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Electric field
A region of space in which a charged object experiences an electric force
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Electric field strength
Force on a 1 coulomb charge in an electric field (force/charge)
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Potential gradient
Potential difference/distance (the rate at which potential changes with distance)
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Thermionic emission
Escape of electrons from the surface of a metal when they are supplied with thermal energy
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Fundamental particle
A particle that cannot be broken up into smaller constituents
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Standard model of particle physics
A theory which identifies 12 fundamental particles from which all matter is made and four fundamental forces that govern reactions between the particles
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Quark
A group of fundamental particles of which the proton and neutron are made
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Lepton
A group of fundamental particles of which the electron is one
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Generation
Family (particles in one generation have a family resemblance to particles in the other generations)
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Fundamental force
A force that cannot be explained in terms of any other force
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Strong nuclear force
A fundamental force that acts on all quarks
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Weak nuclear force
A fundamental force that acts on quarks and leptons and controls beta decay
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Neutrino
A fundamental particle of no charge and negligible mass released during beta decay
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Hadron
Particle made of quarks
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Baryon
Particle made of three quarks
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Meson
Particle made of a quark and an anti-quark
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Antimatter
Has same mass as its matter particle and opposite charge. Annihilates readily with matter
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Positron
Antimatter particle of the electron
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Annihilation
The conversion of mass into energy when matter and antimatter meet
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Inverse square law
The force is inversely proportional to the square of the preparation between two charges
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Coulomb’s law
The force is directly proportional to the product of the charges divided by the square of the separation
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De Broglie wavelength
Planck constant divided by momentum
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Rest mass
Mass of an object when it is at rest
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Rest mass energy
Energy needed to create a particle at rest from nothing
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Linear accelerator
A particle accelerator using an electric field to accelerate particles in a straight line
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Cyclotron
A particle accelerator using magnetic fields to make charged particles move in a circular path
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Centripetal force
Resultant force acting towards the centre of the circle for any body moving with circular motion
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Angular velocity
Angle moved through in radians per second
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Time Period
Time taken for one complete oscillation
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Centripetal acceleration
Acceleration towards the centre of the circle for any body moving at constant speed with circular motion
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Other cards in this set

Card 2

Front

Momentum is conserved in all interactions where no external force acts

Back

Principle of conservation of momentum

Card 3

Front

The rate of change of momentum of a body is directly proportional to the resultant force acting on it

Back

Preview of the back of card 3

Card 4

Front

Total kinetic energy before the collision = the total kinetic energy after the collision

Back

Preview of the back of card 4

Card 5

Front

Total kinetic energy before the collision is greater than the total kinetic energy after the collision (some kinetic energy is transferred into other forms during the collision)

Back

Preview of the back of card 5
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