# Physics - Unit 4 - Definitions

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• Created by: SamNoel
• Created on: 23-03-16 16:59
Conservation of Momentum
In the absence of external forces, the total momentum of a system is conserved
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Newton's Second Law
Rate of change of momentum is directly proportional to the resultant force which acts upon it
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Impulse
Change in momentum of a body
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Simple Harmonic Motion
An oscillation in which the acceleration is directly proportional to the displacement from the mid-point, and is directed towards the mid-point
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Resonance
When the driving force equals the natural frequency and causes the amplitude to rapidly increase
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Damping
When energy is lost to surroundings causing amplitude of an oscillation to decrease
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Gravitational Potential
Work done per unit mass to move a small test mass from infinity to a point
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Electrical Potential
Work done per unit charge to move a positive test charge from infinity to a point
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Induced emf is directly proportional to the rate of change of flux linkage
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Lenz's Law
Induced emf is always in such a direction as to oppose the change that caused it
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Elastic Collision
Both momentum and kinetic energy are conserved
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Inelastic Collision
Momentum is conserved, but kinetic energy is not
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Gravitational Field Strength
Force acting per unit mass at any point
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Electric Field Strength
Force acting per unit charge at any point
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Magnetic Field Strength
Force on one metre of wire carrying a current of one amp at right angles to the magnetic field
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Magnetic Flux Density
Measure of strength of the magnetic field per unit area
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Angular Speed
Angle an object rotates through per second
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Centripetal Acceleration
Force which keeps the object moving in a circle
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Gravitational Potential Difference
Energy needed to move a unit mass
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Electrical Potential Difference
Energy needed to move a unit charge
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Force on a Wire
Force is proportional to the magnetic field strength
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emf induced by changing the magnitude or direction of magnetic flux
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Flux Change
Change in flux of one weber per second will induce an emf of one volt in a loop of wire
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Newton
One Newton will give a 1kg mass, an acceleration of one metre per second
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Linear Momentum
Mass of an object multiplied by its velocity
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One radian is the angle subtended at the centre of a circle by an arc of length equal to the circles radius
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Period
Time taken for an object in circular motion to complete one revolution
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Fields
Region in which a force operates
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Capacitance
Amount of charge stored per volt
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Magnetic Field
Region where a force is exerted on magnetic materials
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Alternator
Generates alternating current
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## Other cards in this set

### Card 2

#### Front

Rate of change of momentum is directly proportional to the resultant force which acts upon it

#### Back

Newton's Second Law

### Card 3

#### Front

Change in momentum of a body

### Card 4

#### Front

An oscillation in which the acceleration is directly proportional to the displacement from the mid-point, and is directed towards the mid-point

### Card 5

#### Front

When the driving force equals the natural frequency and causes the amplitude to rapidly increase