Keywords + Defintions Flashcards
Pico
10^-12
Nano
10^-9
Micro
10^-6
Milli
10^-3
Centi
10^-2
Kilo
10^3
Mega
10^6
Giga
10^9
Tera
10^12
Newton
The force which gives a mass of 1kg an acceleration of 1ms^-2
Joule
The work done by a force of 1N moving an object 1N in the direction of the force
Watt
The power transferred by one joule per second
Displacement
The distance moved by an object in a particular distance
Instantaneous speed
The speed at the precise instant that is measured. An example would be a car’s speedometer
Average speed
The speed calculated during a period of time
Speed
Rate of change of distance.
Speed = change in distance/time
Velocity
Rate of change displacement
Velocity = change of displacement / time
Acceleration
Rate of change of velocity.
Acceleration= change in velocity/time
Density
Density = Mass/volume
Torque of a couple
One of the forces x perpendicular distance between the forces
Moment of a force
Force x perpendicular distance from pivot
Power
The rate of work done
Power = energy/time
Work done by a force
Force x distance moved in the direction of the force
Power
The rate of work done
Power = energy/time
Force constant of a spring
Force per unit extension
Scalar quantity
A quantity with magnitude only
Vector quantity
A quantity with both magnitude and direction
Terminal velocity
The velocity of a falling object when Weight=drag
Centre of gravity
A point where the entire weight of an object appears to act
Thinking distance
The distance recalled by the car in the time taken by the driver to react
Braking distance
The distance travelled by the car after the brakes are applied until the car stops
Stopping distance
Thinking distance + braking distance
Principle of conservation of energy
Energy cannot be greeted or destroyed; it can only be transferred into other forms
Principle of moments
For an object in equilibrium, the sum of the clockwise moments about a point = the sum of anti-clockwise moments about the same point
Hooke’s law
Extension of a spring is proportional to the force applied as long as the elastic limit is not exceeded
Stress
Force/Area
Strain
Extension/original length
Young’s modulus
Young’s modulus = stress/strain
This is only the case if the elastic limit is not reached
Ultimate tensile strength
The breaking stress of a material
Elastic deformation
Material returns to original shape when the force is removed
Plastic deformation
Material does not return to original shape when the force is removed
Coulomb
The charge transferred by a 1 ampere current in one second
Volt
1 joule per coulomb
