Physics Definitions (Module 5)

Gravitational potential

The work done per unit mass to bring an object from infinity to a point in the gravitational field

Thermal equilibrium

When there is no net heat flow between bodies in thermal contact

Specific heat capacity

The energy required to raise the temperature of a unit mass of a substance by one kelvin

Specific latent heat of vaporisation

The thermal energy required per unit mass in order to change a liquid into a gas at constant temperature

Specific latent heat of fusion

The thermal energy required per unit mass in order to change a liquid into a solid at constant temperature

Internal energy

The total sum of the randomly distributed kinetic energy and potential energy of atoms/molecules

Boyle’s law

Pressure is inversely proportional to volume for a fixed mass of gas at constant temperature

Newton’s second law

The resultant force acting on an object is proportional to the rate of change of momentum and the change in momentum occurs in the same direction as the resultant force

Centripetal force

A resultant force that acts perpendicularly to the direction of motion, instantaneously towards the centre of a circle

Work done

Force multiplied by the distance moved in the direction of the force

Simple harmonic motion (SHM)

Acceleration is directly proportional to the displacement from the equilibrium position and is always directed towards the equilibrium position

Isochronous oscillator

An oscillator that has the same time period regardless of amplitude

Free vibration

The oscillatory motion of a system, displaced from its equilibrium position and then allowed to oscillate without any external periodic driving forces. The system oscillates at its natural frequency

Forced vibration

The oscillatory motion of a system where an external periodic driving force is applied. The system oscillates at the driving frequency

Newton’s law of gravitation

The gravitational force of attraction exerted on one object by another object is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres of mass

Gravitational field strength

Force per unit mass at a point in a gravitational field

Kepler’s first law

The orbit of a planet is an ellipse with the Sun at one of the two foci

Kepler’s second law

A line segment joining a planet and the Sun sweeps out equal areas during equal intervals of time

Kepler’s third law

The cube of the planet’s mean distance from the Sun divided by the square of the orbital period is the same for all planets