module 5 definitions Flashcards
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 (The two bodies are at the same temperature).
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.
Boyle’s law
Pressure is inversely proportional to volume for a fixed mass of gas at constant temperature.
Centripetal force
A resultant force which acts perpendicularly to the direction of motion, instantaneously towards the centre of a circle
Simple harmonic motion (SHM)
Acceleration is proportional to the displacement from equilibrium position and acceleration 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.
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 the Earth.
Doppler effect
The observed change in the frequency/wavelength of waves due to the source of the waves moving relative to the observer
natural frequency of vibration
(for an oscillating body)
the frequency at which an object oscillates when free to do so
forced frequency
(for an oscillating body)
the frequency at which an object is made to oscillate
workfunction of a metal
the minimum energy required to eject an electron from a metal surface
