Further Mechanics & Thermal

Question 1

Absolute scale

Answer 1

Temperature scale in kelvins (K) defined in terms of absolute zero, 0K, and the triple point of water, 273.16K, which is the temperature at which ice, water and water vapour are in thermal equilibrium.

Question 2

Absolute temperature T

Answer 2

…in kelvin = temperature in degrees C +273(.15)

Question 3

Absolute zero

Answer 3

The lowest possible temperature, the temperature at which an object has minimum internal energy.

Question 4

Angular displacement

Answer 4

The angle an object in circular motion turns through. If its time period is T and its frequency is f, its angular displacement in time t, in radians = 2pift = 2pi*t/T

Question 5

Angular frequency (omega)

Answer 5

For an object oscillating at frequency f in simple harmonic motion, its angular frequency = 2pif

Question 6

Angular speed (omega)

Answer 6

The rate of change of angular displacement of an object in circular (or orbital or spinning) motion.

Question 7

Boiling point

Answer 7

The temperature at which a pure liquid at atmospheric pressure boils.

Question 8

Boltzmann constant

Answer 8

The molar gas constant divided by the Avogadro number.

Question 9

Boyles Law.

Answer 9

For a fixed mass of gas at constant temperature, its pressure X its volume is constant. The gas that obeys Boyles’ Law is said to be an ideal gas.

Question 10

Brownian motion

Answer 10

The random and unpredictable motion of a particle such as a smoke particle caused by molecules of the surrounding substance colliding at random with the particle. Its discovery provided evidence for the existence of atoms.

Question 11

Celsius scale

Answer 11

Temperature in degrees Celsius or °C is defined as absolute temperature in Kelvins -273.15. This definition means that the temperature of pure melting ice is 0°C.And the temperature of steam at standard atmospheric pressure is 100°C

Question 12

Centripetal acceleration

Answer 12

Acceleration on an object required to keep it in circular motion. a = v²/r = ω²r.

Question 13

Charles’ law

Answer 13

For a fixed mass of an ideal gas at constant temperature, its volume is directly proportional to its absolute temperature in Kelvin.

Question 14

damped oscillations

Answer 14

Oscillations that reduce in amplitude due to the presence of resistive forces such as friction and drag.

1. For a lightly damped system, the amplitude of oscillations decreases gradually.
2. For a heavily damped system displaced from equilibrium then released, the system slowly returns to equilibrium without oscillating.
3. For a critically damped system, the system returns to equilibrium in the least possible time without oscillating.

Question 15

forced vibrations

Answer 15

vibrations (oscillations) of a system subjected to an external periodic force.

Question 16

free vibrations

Answer 16

vibrations (oscillations) where there is no damping and no periodic force acting on the system, so the amplitude of the oscillations is constant.

Question 17

heat (Q)

Answer 17

energy transfer due to difference of temperature.

Question 18

heat capacity

Answer 18

the energy needed to raise the temperature of an object by 1K

Question 19

ideal gas

Answer 19

a gas under conditions such that it obeys Boyle’s law.

Question 20

ideal gas equation

Answer 20

pV = nRT, where p is the gas pressure, V is the gas volume, n is the number of moles of gas, T is the absolute temperature and R is the molar gas constant.

Question 21

Internal energy

Answer 21

Of an object is the sum of the random distribution of the kinetic and potential energy is of its molecules

Question 22

Kinetic theory of a gas

Answer 22

1) Assumptions; A glass consists of identical point molecules which do not attract one another. The molecules are in continual random motion colliding elastically with each other and with the container.
2) pV=1/3Nmc², p-pressure, V-volume of container, N - number of molecules, m-mass of each molecule, c²- The mean square speed of the gas molecule

Question 23

Latent heat of fusion

Answer 23

The energy needed to change the state of the solid to a liquid without change of temperature

Question 24

Latent heat of vaporisation

Answer 24

The energy needed to change the state of a liquid to a vapour without change of temperature

Question 25

mean kinetic energy

Answer 25

for a molecule in a gas at absolute temperature T, its mean KE is 3kT/2, where k is the Boltzmann constant

Question 26

melting point

Answer 26

the temperature at which a pure substance melts

Question 27

molar gas constant

Answer 27

R, where pV=nRT

Question 28

molar mass

Answer 28

the mass of one mole of a substance

Question 29

molarity

Answer 29

the number of moles in a certain quantity of a substance

Question 30

mole

Answer 30

one mole of a substance consisting of identical particles is the quantity of substance that contains 6.02x10²³ particles of the substance

Question 31

Natural Frequency

Answer 31

The frequency of free oscillations of an oscillating system

Question 32

Periodic Force

Answer 32

A force that varies regularly in magnitude with a definite time period

Question 33

Pressure law

Answer 33

for a fixed mass of an ideal gas at constant volume, its pressure is directly proportional to its absolute temperature

Question 34

Radian

Answer 34

1 Radian= 360/2π degrees , 2π Radians= 360 degrees

Question 35

Resonance

Answer 35

The amplitude of vibration of an oscillating system subjected to a periodic force is largest when the periodic force has the same frequency as the resonant frequency of the system. for a lightly damped system, the frequency of the periodic force = natural frequency of the oscillating system. At resonance, the system vibrates such that its velocity is in phase with the periodic force.

Question 36

Resonant frequency

Answer 36

the frequency of an oscillating system in resonance

Question 37

Root mean square speed

Answer 37

square root of the mean value of the square of the molecular speeds of the molecules of a gas

Question 38

simple harmonic motion

Answer 38

motion of an object where the acceleration towards equilibrium position is proportional to the displacement of the object from equilibrium and in the opposite direction

Question 39

specific heat capacity c

Answer 39

of a substance is the energy needed to raise the temperature of 1kg of the substance by 1K without changing the state (Q = mcΔT)

Question 40

specific latent heat of fusion

Answer 40

of a substance is the energy needed to change the state of 1kg of solid to liquid without a change in temperature (Q = ml)

Question 41

specific latent heat of vaporisation

Answer 41

of a substance is the energy needed to change the state of 1kg of liquid to vapour without a change in temperature (Q = ml)

Question 42

sublimation

Answer 42

change of state when a solid changes directly into vapour

Question 43

temperature

Answer 43

degree of hotness of an object defined in terms of fixed points e.g. the triple point of water

Question 44

thermal energy

Answer 44

internal energy of an object due to temperature

Question 45

thermal equilibrium

Answer 45

when no overall heat transfer occurs between two objects at the same temperature

Question 46

Uniform circular motion

Answer 46

Motion of an object moving at constant speed along a circular path.