Physics

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.

weight (Fg)

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

Describe a gravitational field

A region in space where a mass will experience a force

Define gravitational field

The force acting per unit mass

Mass

The amount of matter in an object.

Coulombs law

Two point charges exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges.

Describe an electric field

A region of space in which an electric charge experiences a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point.

Magnetic flux linkage

The product of the number of turns on the coil and the flux through the coil

Faradays law of electromagnetic induction

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

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

Vector

A physical quantity that has both magnitude and direction.

Scalar

A physical quantity

Resultant vector

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

Distance

The length of the path travelled

Displacement

A change in position

The rate of change of distance

The rate of change of displacement

Acceleration

The rate of change of velocity

Normal force

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

Frictional force due to a surface

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

Newtons first law

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

Inertia

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

Newtons second law

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

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

Potential difference

The work done per unit positive charge

Current

The rate of flow of charge

Ohms law

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

Emf

The total energy supplied per coulomb of charge by the cell

Linear momentum

The product of the mass and velocity of the object

Newtons second law in terms of momentum

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

Isolated system

A system that has no external forces acting on it.

The law of conservation of linear momentum

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

Elastic Collison

A collision in which both momentum and kinetic energy are conserved

Inelastic Collison

A collision in which only momentum is conserved.

Impulse

The product of the net force and the contact time

Work done on an object by a force

The product of the of 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 a result of the objects motion

Mechanical energy

The sum of gravitational potential and kinetic energy at a point

The law of conservation of energy

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

The principle of conservation of mechanical energy

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

The work-energy theorom

The 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.

Efficiency

The ratio of output power to input power

Describe the photoelectric effect

The process that occurs when light shines on a metal and electrons are ejected

State the significance of the photoelectric effect

It establishes the quantum theory and illustrates the particle nature of light

Threshold frequency

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

Work Function

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