Thermal Physics

Question 1

What is Boyle’s Law?

Answer 1

Pressure is INVERSELY PROPORTIONAL to Volume

Question 2

What is Charles’ Law?

Answer 2

Temperature is DIRECTLY PROPORTIONAL to Volume

Question 3

What is the Pressure Law?

Answer 3

Pressure is DIRECTLY PROPORTIONAL to Temperature

Question 4

What does NOT change while a substance is changing from a liquid to a solid?

Answer 4

The Temperature

Question 5

What is the theoretical point at which all molecular motion ceases?

Answer 5

Absolute Zero

Question 6

What type of energy means the sum of the potential and kinetic energies?

Answer 6

Internal Energy

Question 7

What type of quantity is temperature?

Answer 7

Scalar

Question 8

What is a gas that obeys the gas laws at all temperatures and pressures called?

Answer 8

An Ideal Gas

Question 9

What is the type of latent heat energy involved in the process of changing from solid to liquid?

Answer 9

Latent Heat of Fusion

Question 10

What type of energy do we assume is zero for an ideal gas?

Answer 10

Potential Energy

Question 11

If there is no net heat energy flow between two bodies they are said to be in what?

Answer 11

Thermal Equilibrium

Question 12

What type of latent heat is involved in changing a liquid to a gas?

Answer 12

Latent heat of Vaporisation

Question 13

Using pV = 1/3 Nmc² it can be shown that: p = 1/3 ρc² , how can this equation be proved?

Answer 13

Using the definition of density and the fact that the gas’ total mass will N x m

Question 14

What is the equation of state for n moles of an ideal gas?

Answer 14

pV = nRT

Question 15

State three assumptions that are made in the derivation pV=1/3Nmc² (Molecular Kinetic Theory)

Answer 15

● All particles are identical
● Collisions of gas molecules are elastic
● Intermolecular forces are negligible (except during collisions)

Question 16

What is Internal Energy?

Answer 16

The sum of the potential and kinetic energies of a system

Question 17

How can you increase the thermal energy of a system?

Answer 17

By heating it up or doing work on the object

Question 18

Explain the energy changes that occur during a change of state

Answer 18

Potential energies of the particles change but the kinetic energy does not

Question 19

What equation can be used to determine the energy required to change the temperature of a substance?

Answer 19

Q =mcΔT

Question 20

What is the equation to work out the energy for change of state?

Answer 20

Q =ml

Question 21

What is the Ideal Gas equation?

Answer 21

pV = nRT

Question 22

What is the first law of thermodynamics?

Answer 22

ΔU = Q - W

Question 23

What is the Specific Heat Capacity of a substance?

Answer 23

The energy required to raise the temperature of 1kg by 1K

Question 24

What is the Specific Latent Heat of a substance?

Answer 24

The energy required to change the state of 1kg, whilst keeping the temperature constant

Question 25

What is an Ideal Gas?

Answer 25

A gas where: the molecules don't interact with each other, and the molecules are thought to be perfect spheres

Question 26

What is the internal energy of an Ideal Gas equal to?

Answer 26

The sum of the kinetic energy of all its particles

Question 27

In an Ideal Gas, how would increasing the volume change the temperature of the gas, whilst the pressure remains constant?

Answer 27

As volume increases, so does the temperature

Question 28

Explain how increasing the temperature of a balloon, whist keeping the volume the same, will increase the pressure

Answer 28

● Average KE increases ● Particles travel faster ● More frequent collisions ● Particles exert greater force ● Increases rate of change of momentum

Question 29

What is Absolute Zero?

Answer 29

At -273°C, where objects have no KE

Question 30

What is Avogadro's Constant? (In words)

Answer 30

The number of atoms there are in one mole of a substance

Question 31

True or False: "All collisions between particles and between particles and the wall are elastic" is an assumption of an Ideal Gas?

Answer 31

True

Question 32

State an assumption of an Ideal Gas related to time

Answer 32

The time for each collision is negligible in comparison to the time between collisions

Question 33

What is meant by the root mean square speed?

Answer 33

The square root of the mean of the squares of the speeds of the molecules

Question 34

What is Brownian Motion?

Answer 34

Very small objects have random motion in a liquid or gas due to random bombardment by molecules in the substance

Question 35

What is the mnemonic to remember the assumptions of the kinetic theory of gases?

Answer 35

RAVED

Question 36

In the mnemonic for remembering the assumptions of the kinetic theory of gases, what does R stand for?

Answer 36

Random motion

Question 37

In the mnemonic for remembering the assumptions of the kinetic theory of gases, what does A stand for?

Answer 37

Attraction - there is none between particles

Question 38

In the mnemonic for remembering the assumptions of the kinetic theory of gases, what does V stand for?

Answer 38

Volume - molecules/particles have negligible volume compared to that of the gas

Question 39

In the mnemonic for remembering the assumptions of the kinetic theory of gases, what does E stand for?

Answer 39

Elastic collisions - Kinetic energy is conserved

Question 40

In the mnemonic for remembering the assumptions of the kinetic theory of gases, what does D stand for?

Answer 40

Duration of collisions is very short compared to time between

Question 41

What is the formula for the force exerted by a particle of an Ideal Gas on the wall of its container, according to the kinetic theory of gases?

Answer 41

F = -mv²/L