Unit 1 Flashcards
Newton’s second law
Acceleration of an object is directly proportional to the magnitude of the force and inversely proportional to the mass of the object
Newton’s third law
For every action, there is an equal and opposite reaction
Principle of moments
The total clockwise moments equals the total anti-clockwise moments (about the same point) when in equilibrium
Moment of force about a point
The product of force and the perpendicular distance (from point to the line of action of the force)
Resistivity
The resistance of 1 m of material of cross sectional area 1 m^2
Vector
A vector quantity has a magnitude unit and DIRECTION
Scalar
A scalar quantity has a magnitude and unit and NO direction
Conservation of energy
Energy cannot be created or destroyed but it can change from one form to another
Hooke’s law
Extension is directly proportional to applied load provided the limit of proportionality is not exceeded
Potential difference
Energy generated for every coulomb passing between them
Ohm’s law
Potential difference across a conductor is proportional to current through it
Projectile motion
(Uniformly) accelerated motion in one direction, constant speed in the perpendicular direction
Power
Power is the rate of doing work
Efficiency
Efficiency is the fraction on input energy that does work
Strain
Ratio of extension to (unstretched) length
Base units
A unit which all other units are derived. Kg- kilogram m-meter s-second A-ampere Mol-Mole K-kelvin
Electromotive force
Energy converted from other forms to electrical energy when unit charge passes through it
Work
The product of force and distance moved in the direction of the force
Current
The rate of flow of charge
The volt
One joule of energy is dissipated per coulomb of charge
Derived unit
Unit made up from a combination of two or more base units
Ultimate tensile stress
Maximum stretching for per unit area without breaking
Young’s modulus
The ratio of the stress of a material to the strain of the material
Newton’s first law
An object will remain at rest or in uniform motion in a straight line unless acted upon by an external force
Ohmic and non ohmic behaviour
Ohmic behaviour means Potential difference across a conductor is proportional to current through it
Non ohmic means the PD is inversely proportional
Electrical power
The rate at which electrical energy is converted into other forms by a circuit or component
