# Shared Flashcard Set

## Details

OCR A Physics AS defintions
Defintion of all the terms you need to know
54
Physics
04/18/2014

Term
 Absorption line spectrum
Definition
 A dark line of a unique wavelength seen in a continuous spectrum. This is caused by white light passing through a pure sample of a gaseous element. The electrons absorb photons with specific wavelengths/energies relative to the energy levels they can reach.
Term
 Acceleration
Definition
 The rate of change of an object's velocity.
Term
 Average speed
Definition
 The total distance travelled by an object divided by the total time taken.
Term
 Braking distance
Definition
 The distance travelled by a vehicle once the brakes are applied until it comes to a stop. Braking distance is affected by friction (brakes, tyres and road) and the motion of the object.
Term
 Brittle
Definition
 A material that shows none or little plastic deformation before breaking
Term
 Centre of gravity
Definition
 The point where the entire weight of an object appears to act from. Essential for solving moment questions.
Term
 Components of a vector
Definition
 A vector can be separated into two vectors. One in the horizontal direction and one in the vertical direction.
Term
 Compressive
Definition
 A force that sqeezes an object
Term
 Density
Definition
 The mass per unit volume of a substance.
Term
 Displacement
Definition
 The distance travelled in a particular direction from the origin
Term
 Ductile
Definition
 Describes a matereal which shows significant plastic deformation. Can be easily shaped.
Term
 Efficiency
Definition
 The ratio of useful energy out to enrgy put in.
Term
 Elastic
Definition
 Describes a material which returns to its original shape when the force is removed.
Term
 Elastic limit
Definition
 The amount of stress/force beyond which an object will not return to its original shape.
Term
 Elastic potential energy
Definition
 Energy stored in a streched or compressed object
Term
 Electronvolt
Definition
 A unit used for very small amounts of energy. The energy gained by an electron accelerated through a potential difference of 1 Volt
Term
 Emission line spectrum
Definition
 A bright line of a unique wavelength/energy emitted by a substance when the electrons fall from a high energy level to a lower energy level.
Term
 Equilibrium
Definition
 An object with a constant velocity(stationary or moving in a straight line at a constant speeed) or angular velocity (in moments)
Term
 Extension
Definition
 The change in length of a material from its original length.
Term
 Force or spring constant
Definition
 The ratio of force to extension for a spring or wire.
Term
 Gravitational potential energy
Definition
 Energy stored by an object due to its position in the a gravitational field.
Term
 Ground state
Definition
 The lowest energy level an electron can occupy in an atom.
Term
 Hooke's law
Definition
 Force is proprtional to extension for an elastic material
Term
 Inertia
Definition
 A measure of the mass of an object. How hard it is to change the motion of an object.
Term
 Instantaneous speed
Definition
 The speed of an object measured over a very small period of time
Term
 Kinetic energy
Definition
 Energy of an object due to its motion
Term
 Mass
Definition
 The amount of material within an object
Term
 Moment
Definition
 The truning effect caused by a force on a pivotted object. Force multiplied by perpendicular distance between force and pivot
Term
 Newton
Definition
 The force that will give 1 kg an acceleration of 1m/s2.
Term
 Photon
Definition
 A particle which represents an electromagentic wave.
Term
 Plastic deformation
Definition
 A material will not return to its original shape when the force is removed.
Term
 Power
Definition
 The rate at which work is done
Term
 Principle of moments
Definition
 The sum of clockwise moments about a point is equal to the sum of the anti clockwise moets about the same point leasding to an object being in equilibrium
Term
 Resultant force
Definition
 The net force acting on an object
Term
 Scalar
Definition
 A quantity with size/magnitude only.
Term
 Speed
Definition
 Rate of change of the distance moved by an object
Term
 Stopping distance
Definition
 The sum of think and braking distance
Term
 strain
Definition
 The extension per unit length produced by a tensile or compressive froce
Term
 stress
Definition
 Force acting per unit cross sectional area on a material
Term
 Tensile
Definition
 A term used to denote tension or pull
Term
 Terminal velocity
Definition
 The constant velocity of an object flowing through a fluid (gas or liquid). The net force on the object is zero.
Term
 Thinking distance
Definition
 THe distance travelled whilst the driver reacts to a situation where they are meant to stop.
Term
 Threshold frequency
Definition
 The minimum frequency of the electromagnetic radiation that will eject electrons from the surface of a metal.
Term
 Threshold voltage
Definition
 The minimum forward bias voltage across a light emitting diode (LED) when it starts to conduct and emit light.
Term
 Torque
Definition
 The product of two forces in opposites direction, an equal distance from the pivot.
Term
 Transition
Definition
 When an electron moves from one energy level to another
Term
 Ultimate tensile force
Definition
 The breaking stress of a material
Term
 Vector
Definition
 A quantity that has size and direction
Term
Definition
 Using a scale drawing to combine vectors to find the resultant vector
Term
 Velocity
Definition
 The rate of change of the displacement of an object
Term
 Weight
Definition
 The force on a mass caused by a gravitational field
Term
 Work done
Definition
 The amount of energy transformed in a situation
Term
 Work function
Definition
 THe minimum energy required by a single electron to escape from the surface of a metal
Term
 Youngs modulus
Definition
 Ratio of stress to strain. Describes the stiffness of a material.
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