OCR A level physics module 5 definitions

internal energy

The total sum of randomly distributed kinetic energy and potential energy of atoms/molecules in a substance

thermal equilibrium

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

latent heat of vaporization

the thermal energy required per unit mass to change a substance from liquid to gas at a constant temperature

latent heat of fusion

the thermal energy required per unit mass to change a substance from liquid to solid at a constant temperature

Boyle's Law

pressure and volume are inversely proportional for a fixed mass of gas at a constant temperature

Centripal force

a resultant force which acts perpendicularly to the direction of motion, instantaneously towards the Centre of the circle

Simple Harmonic Motion (SHM)

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

Isochronous oscillator

An oscillator that has the same 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

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

Gravitational potential

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

Energy level

A discrete amount of energy that an electron within an atom is allowed to possess

Parsec

The distance from a base length of 1 AU that subtends an angle of 1 arc second

Cosmological Principle

the universe is homogeneous and isotropic on large scales and the laws of physics are universal

Hubble's Law

The recessional speed of a galaxy is proportional to its distance from earth

Doppler effect

The observed change in frequency/wavelength of waves due to the source of the waves moving relative to the observer

newtons 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