Year 13 physics definitions topic order

Question 1

Absolute or thermodynamic temperature scale

Answer 1

An absolute or thermodynamic temperature scale is independent of the proerties of any specific substance. It is measured in Kelvin, K.

Question 2

Absolute zero

Answer 2

Absolute zero (0 K) is the temperature at which a substance has minimum internal energy; this is the lowest limit for temperature.

Question 3

Thermal equilibrium

Answer 3

Thermal equilibrium occurs when two objects are in contact with each other and are the same temperature; this means there is no net heat flow between them.

Question 4

The kinetic model of matter

Answer 4

The kinetic model of matter is where all matter is made of very small particles (atoms, molecules or ions) which are in constant motion

Question 5

Internal energy

Answer 5

Internal energy is the sum of the kinetic and potential energies of all the atoms or molecules within a system.

Question 6

Brownian motion

Answer 6

Brownian motion is the random movement of small visible particles suspended in a fluid due to collisions with much smaller, randomly moving atoms or molecules of the fluid.

Question 7

Specific heat capacity

Answer 7

Specific heat capacity of a substance is the energy needed to raise the temperature of 1 kg of the substance by 1 K.

Question 8

Specific latent heat of fusion.

Answer 8

Specific latent heat of fusion of a substance is the energy needed to change the phase of 1 kg of the substance from solid to liquid.

Question 9

Specific latent heat of vaporisation.

Answer 9

Specific latent heat of vaporisation of a substance is the energy needed to change the phase of 1 kg of the substance from liquid to gas.

Question 10

The mole.

Answer 10

A mole of a substance will contain 6.02 x 10²³ particles. This number is called Avagadro’s constant.

The relative atomic mass of a substance in g, contains 1 mole of particles.

Question 11

An ideal gas

Answer 11

An ideal gas is one that has internal energy only in the form of random kinetic energy.

Question 12

Boyle’s Law

Answer 12

Boyle’s Law states that the volume of a fixed mass of gas is inversely proprtional to the pressure exerted on the gas, under conditions of constant temperature.

PV = constant

Question 13

Radian

Answer 13

One radian is the angle subtended at the centre of a circle by an arc equal in length to the radius subtended.

Question 14

Period

Answer 14

Period is the time needed for one complete cycle of vibration to pass a given point or for one complete revolution incircular motion.

Question 15

Angular velocity

Answer 15

Angular velocity is the rate of angular rotation, measure in radians per second.

Question 16

Centripetal acceleration

Answer 16

Centripetal acceleration is the acceleration of an object moving with uniform circular motion.

It is directed radially inwards towards the centre of the circle, perpendicular to the velocity vector at any instant.

Question 17

Centripetal force

Answer 17

Centripetal force is the resultant force on an object causing it to move in a circular path, and is directed towards the centre of the circle.

Question 18

Displacement (SHM)

Answer 18

Displacement (SHM) is the distance an object is from its equilibrium position. It may be + or -.

Question 19

Amplitude (SHM)

Answer 19

Amplitude (SHM) is the maximum displacement.

Question 20

Frequency (SHM)

Answer 20

Frequency (SHM) is the number of oscillations per second at any point.

Question 21

Isochronous

Answer 21

Isochronous oscillations have a constant time period. All SHM oscillations are isochronous even though the amplitude might decrease due to damping.

Question 22

Simple harmonic motion

Answer 22

SHM occurs when the acceleration is directly proportional to the displacement from a fixed point, and always directed towards that point.

Question 23

Damping

Answer 23

Damping forces reduce the amplitude of an oscillation over time due to energy being removed from the system.

Question 24

Resonance

Answer 24

Resonance occurs when the driving frequency equals the natural frequency of the system being forced to oscillate. This results in the body vibrating at its natural frequency and maximum amplitude.

Question 25

Free oscillations

Answer 25

Free oscillations occur when there is no external periodic force. The system oscillates at its natural frequency.

Question 26

Natural frequency

Answer 26

Natural frequency is the frequency at which a system will oscillate when undergoing free oscillations.

Question 27

Forced oscillations

Answer 27

Forced oscillations occur when an external or driving force is applied to keep the body oscillating. The system oscillates at the frequency of the driving force.

Question 28

Driving frequency

Answer 28

Driving frequency is the frequency of the driving force applied to an oscillating object.

Question 29

Gravitational field

Answer 29

Gravitational field is the region around a body in which other bodies will feel a force due to the mass of the body.

Question 30

Gravitational field strength

Answer 30

Gravitational field strength is the force acting per unit mass at that point.

Question 31

Newton’s law of gravitation

Answer 31

Newton’s law of gravitation states that a particle attracts every other particle in the universe 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.

Question 32

Kepler’s third law

Answer 32

Kepler’s third law states that the square of the period of a planet orbiting the Sun is proportional to the radius of its orbit cubed.

Question 33

Geostationary orbit

Answer 33

Geostationary orbit is one which has the same time period and orbital direction as the rotation of the Earth (i.e. 24 hours) and is in the equatorial plane.

Question 34

Gravitational potential

Answer 34

Gravitational potential at a point in a gravitational field is defined as the work done in moving unit mass from infinity (where gravitational potential is zero) to that point.

Question 35

Gravitational potential energy

Answer 35

Gravitational potential energy of a mass m in a radial gravitational field caused by mass M a distance r from M is given by -GMm/r