# Mechanics Definitions

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• Created by: Emma Gray
• Created on: 19-05-14 18:03
Scalar and vector quantities
Scalar has magnitude only, e.g. speed Vector has both magnitude and direction e.g. velocity
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Displacement
The distance moved in a stated direction
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Speed
The rate of change of distance
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Instantaneous speed
The gradient at a point on a DT graph
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Average Speed
total distance travelled/the total time taken
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Velocity
The rate of change of displacement
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Acceleration
The rate of change of velocity
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The Newton
The force required to accelerate 1kg by 1ms-2
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center of gravity
the point at which the entire weight of an object seems to act
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the moment of a force
force x perpendicular distance between the pivot and force
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torque of a couple
one force x the perpendicular distance between the forces
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Stress
force/cross-sectional area
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strain
extension/origional length
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young modulus
stress/strain (as long as the young modulus is not exceeded)
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brittle
only behaves elastically / it breaks at its elastic limit
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Ultimate tensile strength
the maximum stress that can be applied to an object before it breaks
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work done by a force
force x distance moved in the direction of the force
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elastic deformation
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plastic deformation
when the load is removed the material will not return to its original shape (it has been permanently deformed)
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elastic limit
the maximum load that can be applied to an object so that it will regain its original length once the load is removed
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spring constant
where hookes law is obeyed. force per unit extension
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the joule
when a force of 1N moves 1m in the direction of the force the work done is 1J
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power
the rate of work done
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the watt
one watt is one joule per second
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pressure
force/area
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density
mass/volume
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Thinking distance
the distance travelled from seeing the reason to brake and applying the brakes
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Braking distance
the distance travelled by the car whilst decellerating to a stop
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Stopping distance
thinking distance + braking distance
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principle of moments
for equilibrium the sum of the clockwise moments about a pivot is equal to the sum of the anticlockwise moments around the same pivot
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conditions for an object to be in equilibrium
net force and net moment to equal 0
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hookes law
force is directly proportional to extension as long as the eastic limit is not exceeded
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## Other cards in this set

### Card 2

Displacement

#### Back

The distance moved in a stated direction

Speed

### Card 4

#### Front

Instantaneous speed

### Card 5

Average Speed

#### Back

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Very concise and effective for memorising key terms, finally learnt the definition of CoG. Thank You!

Report

Very concise and effective for memorising key terms, finally learnt the definition of CoG. Thank You!

Report

Very concise and effective for memorising key terms, finally learnt the definition of CoG. Thank You!

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