Key Definitions - Circ Motion, SHM, g-fields, E-Fields

Amplitude

The maximum displacement from the equilibrium position

Angular displacement

The angle in radians, about a fixed axis, that a rotating object has travelled through.

Capacitance

The charge stored per unit potential difference

Centripetal acceleration

Acceleration towards the centre of a curved or circular path.

Centripetal force

A force causing an object to move in a circle, acting towards the centre of the circle

Coulomb's Law

The force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them

Critically damped

When the resistive forces on a system are just enough to prevent oscillation and the object returns to equilibrium in the minimum possible time

Damping

The removal of energy from an oscillating system.

Dielectric

A material which is an electrical insulator that can be polarised by an applied electric field.

Dielectric constant

The factor by which the electric field between two charges is decreased by the presence of the dielectric, relative to a vacuum

Electric field

An area around a charged object/particle where other charged objects/particles would experience a force.

Electric Field Strength

The force per unit charge on a positive test charge placed in the field at that point. A vector quantity.

Electric potential

The work done per unit charge in bringing a small positive test charge from infinity to a specific point in an electric field.

Electric potential difference

The work done per unit charge moving the charge between two points.

Equipotential surface

All points on an equipotential surface have the same gravitational potential. No work is done against the field or by the field when an object is moved along this surface.

Equipotential lines

All of the points in a gravitational field where the gravitational potential is the same value

Forced oscillation

An oscillation imposed upon a body or system by an external energy source

Free oscillation

An oscillation in which a body or system oscillates at its natural frequency

Geostationary Satellite

A satellite that has the same orbital period(24h) and direction as the earth and orbits on the equatorial plane, and thus remains over the same point on the Earth’s surface. It is used for communications (e.g. TV).

Gravitational Field Strength

The attractive force per kg acting on an object with mass at a specific point in that field

Gravitational potential

The work done per kg moving an object from infinity to a specific point in a gravitational field

Gravitational potential difference

The work done per kg moving an object from one point to another point in the same gravitational field

Gravitational potential energy

The total work done moving an object from infinity to a specific point in a gravitational field (gravitational potential x mass of object in field)

Gravitational Field

A region of space where an object with mass experiences an attractive force

Light Damping

A type of damping in which the amplitude of oscillations decreases gradually over time without completely stopping the motion.

Mechanical Oscillation

A periodic conversion of energy such as from potential energy to kinetic energy to potential energy.

Newton's law of universal gravitation

The attractive force between two objects is directly proportional to the product of the masses and inversely proportional to the square of the distance between them

Neutral point

A point between two or more objects with mass where the overall force due to gravity is 0

Over Damping

Occurs when the damping force is greater than the restoring force, resulting in a slow return to equilibrium without oscillation. This leads to a system that slowly approaches equilibrium.

Polar satellite

A satellite whose orbit takes it over each pole. It is used for weather monitoring and military surveillance. They are closer to the Earth’s surface and so travel faster than geostationary satellites.

Radial field

A field where the field lines converge on a single point or diverge from a single point.

Resonance

Large amplitude vibrations caused when the driving frequency matches the natural frequency of a system

Resonant frequency

The natural frequency at which an object or system oscillates

Simple harmonic motion

The periodic motion in which the restoring force (and thus acceleration) is proportional to the displacement and acts in the opposite direction

Synchronous orbit

An orbit where the orbiting object’s orbital period and direction is the same as the rotational period and direction of the body it orbits.

Uniform field

A field where the field lines are parallel and the field strength is constant