physics ieb definitions

Vector

A physical quantity that has both magnitude and direction

Scalar

A physical quantity that has magnitude only

Resultant vector

A single vector which has the same effect as the original vectors acting together

Distance

Length of path travelled

Displacement

A change in position

Speed

Rate of change of distance

Velocity

Rate of change of position (or displacement)

Acceleration

Rate of change of velocity

Weight (Fg)

The gravitational force the Earth exerts on any object on or near its surface

Normal force (FN)

The perpendicular force exerted by a surface on an object in contact with it

Frictional force due to a surface (Ff)

The force that opposes the motion of an object and acts parallel to the surface with which the object is in contact

Newton's First Law of Motion

An object continues in a state of rest or uniform (moving with constant) velocity unless acted upon by a net or resultant force

Inertia

The property of an object that causes it to resist a change in its state of rest or uniform motion

Newton's Second Law of Motion

When a net force, Fnet, is applied to an object of mass, m, it accelerates in the direction of the net force. The acceleration, a, is directly proportional to the net force and inversely proportional to the mass

Newton's Third Law of Motion

When object A exerts a force on object B, object B simultaneously exerts an oppositely directed force of equal magnitude on object A

Newton's Law of Universal Gravitation

Every particle with mass in the universe attracts every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres

Gravitational field

The force acting per unit mass

Momentum

The product of the mass and velocity of the object

Newton's Second Law in terms of Momentum:

The net force acting on an object is equal to the rate of change of momentum

Impulse (J)

The product of the net force and the contact time

Law of conservation of linear momentum

The total linear momentum of an isolated system remains constant (is conserved)

Elastic collision

A collision in which both momentum and kinetic energy are conserved

Inelastic collision

A collision in which only momentum is conserved

Work done on an object

The product of the displacement and the component of the force parallel to the displacement

Gravitational potential energy

The energy an object possesses due to its position relative to a reference point

Kinetic energy

The energy an object has as a result of the object's motion

Mechanical energy

The sum of gravitational potential and kinetic energy at a point

Law of conservation of energy

The total energy in a system cannot be created nor destroyed; only transformed from to another

Principle of conservation of mechanical energy

In the absence of air resistance or any external forces, the mechanical energy of an object is constant

Work-energy theorem

Work done by a net force on an object is equal to the change in the kinetic energy of the object

Power

The rate at which work is done OR rate at which energy is transferred

Watt

The power when one joule of work is done in one second

Efficiency

The ratio of output power to input power

Coulomb's law

Two point charges in free space or air exert a force on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the the distance between the charges.

Electric field at a point

The force per unit positive charge

Potential difference

The work done per unit positive charge

Current

The rate of flow of charge

Ohm's law

Current through a conductor is directly proportional to the potential difference across the conductor at constant temperature

Resistance

A material's opposition to the flow of electric current

Emf

The total energy supplied per coulomb of charge by the cell

Magnetic flux density

Is a representation of the magnitude and direction of the magnetic field.

Magnetic flux linkage

Product of the number of turns on the coil and the flux through the coil (flux linkage)

Faraday's law of electromagnetic induction

The emf induced is directly proportional to the rate of change of magnetic flux

Lenz's law

The induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux

Diode

A component that only allows current to flow in one direction

Threshold (cut-off) frequency (fo)

the minimum frequency of incident radiation at which electrons will be emitted from a particular metal

Work function (Wo)

the minimum amount of energy needed to emit an electron from the surface of a metal