# Physics (1.1-1.5)

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• Created by: Dan Tran
• Created on: 13-12-17 13:55
QUANTITY
A number x a unit (in S.I)
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SCALAR
A quantity having magnitude
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VECTOR
A quantity having magnitude & direction
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RESOLVING A VECTOR INTO COMPONENTS IN PARTICULAR DIRECTIONS
A vector having same effect as two vectors acting together
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DENSITY
Mass per unit volume
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Force x perpendicular distance from the point to the line of the action of the force
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PRINCIPLES OF MOMENTS
For a system to be in equilibrium, the total anti clockwise moments = total clockwise moments
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CENTRE OF GRAVITY
The point within the body where the entire weight can be considered to act
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DISPLACEMENT
The straight line distance travelled with direction
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MEAN SPEED
Distance per unit time
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MEAN VELOCITY
Displacement per unit time
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INSTANTANEOUS SPEED
Rate of change of distance
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INSTANTANEOUS VELOCITY
Rate of change of displacement
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ACCELERATION
Rate of change of velocity
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TERMINAL VELOCITY
Maximum and constant velocity when the resistances are equal and opposite to the accelerating force.
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FORCE
A push or a pull acted by an external body
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NEWTON'S 3RD LAW
If A apply a force on B, B apply an equal and opposite force on A
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TOTAL F=ma
Mass x acceleration = the vector sum of forces acting on the body a.k.a Resultant force
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MOMENTUM
Mass x velocity
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NEWTON'S 2ND LAW
Rate of change of momentum = Sum of forces acting on a body & takes place in the direction of that force
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PRINCIPLES OF CONSERVATION OF MOMENTUM
In an isolated system, the initial total momentum before a collision = the final total momentum after the collision
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ELASTIC COLLISION
A collision where there's no change in kinetic energy
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INELASTIC COLLISION
A collision where kinetic energy is lost`
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WORK
Force x distance having same direction of the force
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PRINCIPLES OF CONSERVATION OF ENERGY
Energy can't be created or destroyed, it can only be transferred from 1 form to another.
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POTENTIAL ENERGY
An energy possessed by an object by virtue its position
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KINETIC ENERGY
An energy possessed by an object by virtue its motion
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ELASTIC POTENTIAL ENERGY
An energy possessed by an object when it has been deformed due to forces acting on it
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ENERGY
Work done
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POWER
Energy or work done per unit time
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HOOKE'S LAW
Force acting on a spring is directly proportional to its extension from its natural length, provided the extension isn't too great
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SPRING CONSTANT
Force per unit extension
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TENSILE STRESS
Force per unit cross sectional area
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TENSILE STRAIN
Extension per unit original length
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YOUNG'S MODULUS
Stress/strain
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CRYSTAL
Solid in which atoms are arranged in a regular array. There's a long range order within crystal structures
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CRYSTALINE SOLID
Solid consisting of a crystal
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AMORPHOUS SOLID
Atoms arranged randomly
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POLYMERIC SOLID
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DUCTILE MATERIAL
A material that can be drawn out into a wire. This implies that plastic strain occurs under enough stress
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ELASTIC STRAIN
The strain disappearing when the tension is removed and the specimen returns to its original length and shape
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PLASTIC/INELASTIC STRAIN
The strain decreasing slightly when the tension is removed. In a metal, it arises from the movement of dislocation within the crystal structures
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ELASTIC LIMIT
The point beyond which the material becomes permanently stretched so that the material does not return to its original length when the force is removed.
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DISLOCATION IN CRYSTALS
Certain faults in crystals which reduce the stress needed for planes of atoms to slide
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EDGE DISLOCATION
The edge of an intrusive, incomplete plane of atoms
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GRAIN BOUDARIES
The boundaries between crystals (grains) in a polycrystalline structures
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NECKING (DUCTILES FRACTURE)
The characteristics fracture process in a ductile material. The fracture of a rod or wire is preceded by local thinning which increases the stress
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BRITTLE MATERIAL
Material with no region of plastic flow, and fails by brittle fracture under tension
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BRITTLE FRACTURE
The fracture under tension brittle materials by means of crack propagation
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### Card 2

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A quantity having magnitude

SCALAR

### Card 3

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A quantity having magnitude & direction

### Card 4

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A vector having same effect as two vectors acting together

### Card 5

#### Front

Mass per unit volume