Definitions Flashcards
Vector
A quantity defined by 3 things (magnitude, unit,direction)
Scalar
A quantity defined by 2 things (magnitude,unit)
Mass
A measure of the amount of matter of an object
Weight
A measurement of how hard gravity pulling on an object
Density
Mass per unit volume
Hooke’s law
The extension of a spring is directly proportional to the force up to the limit of proportionality
Pressure
The force per unit area
Conservation of energy
Energy cannot be created or destroyed but can be transferred from one form to another
Power
The rate of doing work
Efficiency
The measure of the effectiveness of a device transferring energy into a desired form
Principle of moments
when a body is balanced, the total clockwise moment about a point equals the total anticlockwise moment about the same point.
Centre of mass
The point through which the entire mass of the object appears
Centre of gravity
The point through which the entire weight of an object appears
Atomic mass no.
The no. of protons and neutrons in a atom
Atomic no.
The no. of protons in a atom
Ionisation
When an atom or molecule become charged by gaining or losing an electron to form an ion
Isotope
Atoms of an element with the same atomic no. but different mass no.
Half life
is the time taken for its activity to fall to half of the original activity.
Background radiation
Radioactive materials occur naturally without any obvious source
Newton’s 1st law
The forces on a system are balanced, the object has 2 possible states of motion
Stationary or moving at constant velocity
Fr=0
Newton’s 2nd law
The acceleration of a body is directly proportional to the resultant force
Nuclear Fission
The splitting up of a large heavy nucleus into lighter nuclei with the release of energy
Nuclear Fusion
When light nuclei fuse to create heavier nuclei with the release of energy.
