Mechanics definitions

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Scalar quantity
has no direction, just magnitude (size)
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Vector quantity
has direction and magnitude (size)
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Speed
how fast something is moving, regardless of direction
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Displacement (s)
how far an object's travelled from its starting point in a given direction
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Velocity (v)
the rate of change of an object's displacement
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Acceleration (a)
the rate of change of an object's velocity
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Instantaneous speed
the speed of an object at any given point
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Gravitational field strength (g) [on earth]
9.81 Nkg^-1
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Projectile
an object which is given an initial velocity and then left to move freely under gravity
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Newtons 1st Law
states that the velocity of an object will not change unless a resultant force acts on it
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Newtons 2nd Law
resultant force (N) = mass (kg) x acceleration (ms^-2)
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Newtons 3rd Law
If object A exerts a force on object B, then object B will exert an equal but opposite direction force on object A
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Momentum
p=mv , dependant upon mass and velocity
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Work
amount of energy transferred from one form to another when a force causes a movement of some sort (joules)
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Power
rate of doing work / amount of energy transferred from one from to another per second
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Watt
rate of energy transfer equal to 1 joule per second (Js^-1)
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Efficiency
a measure of how well a device converts the energy you put in into the energy you want it to give out
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Centre of Gravity
is the single point that you can consider an b=objects whole weight to act through (whatever its orientation)
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Principle of moments
states that for a body to be in equilibrium, the sum of the clockwise moments about any point equals the sum of the anti clockwise moments about the same point
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Other cards in this set

Card 2

Front

has direction and magnitude (size)

Vector quantity

Card 3

Front

how fast something is moving, regardless of direction

Card 4

Front

how far an object's travelled from its starting point in a given direction

Card 5

Front

the rate of change of an object's displacement