Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Physics > 3.6.2 Thermal physics > Flashcards

3.6.2 Thermal physics Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

What is the internal energy of a body equal to?

A

The sum of all of the kinetic energies and potential energies of all its particles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How are the kinetic and potential energies of a body distributed?

A

They are distributed randomly

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the two ways of increasing the internal energy of a system?

A
  • Do work on the system to transfer energy to it, such as moving its particles or changing its shape
  • Increase the temperature of the system
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What happens to the internal energy of a substance when its state is changed and why?

A

The internal energy changes, because the potential energy of the system changes, while the kinetic energy of the system is kept constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Describe the state change as water boils.

A

The temperature increases up to 100ºC, after which the energy gained through heating the water is no longer used to increase the temperature, and therefore kinetic energy, but instead is used to break bonds between water molecules so it can change state to water vapour, so the potential energy is increased.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does a horizontal line on a temperature - internal energy graph represent?

A

A boiling or melting point, where the substance is not increasing in temperature as its internal energy increases, as kinetic energy doesn’t change, but its potential energy increases as bonds are being broken between molecules, resulting in a state change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the specific heat capacity of a substance?

A

The amount of energy required to increase the temperature of 1kg of a substance by 1ºC/1K, without changing its state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the specific latent heat of a substance?

A

The amount of energy required to change the state of 1kg of material, without changing its temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are the two types of specific latent heat?

A
  • The specific latent heat of fusion, where a solid changes to a liquid
  • The specific latent heat of vaporisation, where a liquid changes to a gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the specific latent heat of fusion of a substance?

A

The amount of energy required to change 1kg of a solid to 1kg of liquid, without changing its temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the specific latent heat of vaporisation of a substance?

A

The amount of energy required to change 1kg of a liquid to 1kg of gas, without changing its temperature

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What do the gas laws represent?

A

The experimental relationship between pressure, volume, and temperature for a fixed mass of gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why are the gas laws empirical in nature?

A

They are not based on theory but arose from observation and experimental evidence

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the three gas laws?

A

Boyle’s Law, Charles’ Law, and the Pressure Law

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Boyle’s Law?

A

For a fixed mass of gas, when temperature is constant, pressure and volume are inversely proportional, pV=k

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is Charles’ Law?

A

For a fixed mass of gas, when pressure is constant, volume is directly proportional to absolute temperature, V/T=k

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the Pressure Law?

A

For a fixed mass of gas, when volume is constant, pressure is directly proportional to absolute temperature, p/T=k

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the absolute scale of temperature?

A

The kelvin scale

19
Q

What scale of temperature is used in all thermal physics equations?

A

The kelvin scale

20
Q

How do you convert from Celsius to kelvin?

A

K = C + 273

21
Q

What is the value of absolute zero?

A

-273ºC, or 0K

22
Q

What is absolute zero?

A

The lowest possible temperature, in which particles have no kinetic energy and the volume and pressure of a gas are zero

23
Q

What does n represent in thermal physics?

A

The number of moles of gas

24
Q

How many atoms/molecules are in one mole of a substance?

A

6.02x10^23

25
Q

What does N represent in thermal physics?

A

The number of molecules

26
Q

What is molar mass?

A

The mass, in grams, of one mole of a substance

27
Q

How can the molar mass of a substance be found?

A

By finding the relative molecular mass, which is equal to the sum of the nucleons in a molecule of the substance

28
Q

How does the volume of a gas change when it is at constant pressure?

A

Work is done to the gas, usually through the transfer of thermal energy

29
Q

How do you calculate the work done on a gas to change its volume when it is at constant pressure?

A

Work done = p ΔV

30
Q

What is Brownian motion?

A

The random motion of larger particles in a fluid caused by collisions with surrounding particles

31
Q

How can Brownian motion be observed?

A

By looking at smoke particles under a microscope

32
Q

Why is Brownian motion significant?

A

It contributed to the evidence for the existence of atoms

33
Q

Explain Boyle’s law using a simple molecular model.

A
  • Pressure is inversely proportional to volume at constant temperature for a fixed mass of gas
  • So if you increase the volume of a fixed mass of gas, its molecules will move further apart so collisions will be less frequent, therefore pressure decreases
34
Q

Explain Charles’ law using a simple molecular model.

A
  • Volume is directly proportional to temperature at constant pressure for a fixed mass of gas
  • When the temperature of a fixed mass of gas is increased, its molecules gain kinetic energy meaning they will move more quickly, and because pressure, and therefore the frequency of collisions, is constant, the molecules move further apart and volume increases
35
Q

Explain the Pressure Law using a simple molecular model.

A
  • Pressure is directly proportional to temperature at constant volume for a fixed mass of gas
  • When the temperature of a fixed mass of gas is increased, its molecules gain kinetic energy meaning they will move more quickly, and as volume is constant, the frequency of collisions between molecules and their container increases, and they collide at higher speeds therefore pressure is increased
36
Q

What is the difference between the gas laws and the kinetic theory model?

A
  • The gas laws are empirical in nature, meaning they are not based on theory but arose from observation and experimental evidence
  • The kinetic theory model is the opposite and arose from only theory
37
Q

What are the ideal gas assumptions?

A
  • Random motion of molecules
  • Duration of collisions is negligible
  • No intermolecular forces of attraction act between molecules
  • Volume of each particle is negligible compared to value of the whole gas
  • Perfectly elastic collisions between molecules
  • Motion of molecules follows Newton’s laws
  • Molecules move in straight lines between collisions
38
Q

How do you derive the equation pV=(1/3)Nm(crms)^2?

A
39
Q

What does the internal energy of an ideal gas consist of?

A

Kinetic energy of atoms

40
Q

Why is the internal energy of an ideal gas equal to the sum of the kinetic energies of all of its particles?

A

An ideal gas follows the gas laws perfectly, so there is no other interaction other than perfectly elastic collisions between the gas molecules, showing there is no intermolecular forces acting between molecules, and, as potential energy is associated with intermolecular forces, an ideal gas has no potential energy, so its internal energy is equal to the sum of the kinetic energies of all of its particles

41
Q

What is the kinetic energy of a single gas molecule equal to?

A

Average molecular kinetic energy

42
Q

What is the relationship between the kinetic energy of a gas molecule and temperature?

A

The kinetic energy of a gas molecule is directly proportional to temperature, in kelvin, KE=3/2kT

43
Q

Why has knowledge and understanding of the behaviour of a gas changed over time?

A
  • The gas laws were discovered and later explained by the development of the kinetic theory model, but this model wasn’t accepted at first
  • Knowledge and understanding of any scientific concept changes over time in accordance to the experimental evidence gathered by the scientific community

Physics (16 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions