# g481 definitions

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• Created by: leecy555
• Created on: 10-11-13 22:36
Scalar
A physical property with magnitude but not direction eg: speed, distance, temperature and wavelength
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Vector
A quantity with both magnitude and direction eg: velocity, force, acceleration and electric current.
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Displacement
The distance travelled in a particular direction in m.
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Instantaneous speed
The speed of an object at a moment in time- a cars speedometer gives the drivers an instantaneous speed.
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Average speed
A measure of the total distance in a unit time- it tells you how far an object has travelled in 1 second.
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Velocity
The velocity of an object is its displacement per unit time- it's a vector quantity measured in ms-1.
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Acceleration
The acceleration of an object is its rate of change of velocity- it's a vector quantity masured in ms-2.
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The Newton
The newton is a unit of force- 1N can move and object with a mass of 1kg with an acceleration of 1ms-2
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The torque of a couple
The turning effect due to a couple masured in Nm.
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The moment of a force
The turning effect due to a single force- it is calculated with force times th perpendicular distance (Fx|_d) from a given point in Nm
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Thinking distance
The distance travelled by a vehicle from seeing the need to stop to applying the brakes.
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Braking distance
The distance travelled by a vehicle when decelerating to a stop- the distance after the brakes are applied.
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Stopping distance
The thinking distance added to the brakin distance.
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Work done
The product (multiplied together) of a force and the distance moved in the direction of the force= wd, it's the energy converted from one form to another- measured in J.
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The joule
A unit of energy- 1 joule is the work done when a force of 1N moves something by 1m in the direction of the force.
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Power
Power is the rate at which work is done, it is measured in Watts- a unit of power (1W=1J)
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Stress
The force per unit cross-sectional area- measured Nm-2 or Pascals (Pa)
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Strain
The extension per unit length (it has no units- it's dimensionless)
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Young modulus
The ratio between stress and strain (stress/strain) in Nm-2 or Pa.
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Ultimate tensile stress (breaking stress)
The maximum tensile (stretching) force that can ba applied to an object before it breaks
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Elastic deformation
The object can return to its original shape once the deforming force is removed.
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Plastic deformation
Th objectcannot return to its original shape after the deforming force is removed, it becomes perminantly deformed.
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Ductile
A materials ability to deform under tensile stress.
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Brittle
A material that distorts very little even when subject to a large stress and does not exhibit any plastic deformation.
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Terminal velocity
The velocity at which an object's drag is equal to its accelerating force- there is no resultant force and zero acceleration.
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Equilibrium
When there is zero resultant force acting on an object.
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Pressure
Force per unit area in Pa.
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Densile
The mass per unit volume in kgm-3.
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Centre of mass
The point at which the entire weight of an object can be considered to act.
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Principle of conservation of energy
Physical law- eergy cannot be created or destroyed, just transformed into another sorm or to another place in a closed system.
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## Other cards in this set

### Card 2

#### Front

A quantity with both magnitude and direction eg: velocity, force, acceleration and electric current.

Vector

### Card 3

#### Front

The distance travelled in a particular direction in m.

### Card 4

#### Front

The speed of an object at a moment in time- a cars speedometer gives the drivers an instantaneous speed.

### Card 5

#### Front

A measure of the total distance in a unit time- it tells you how far an object has travelled in 1 second.