Deck 1

Question 1

Intensive Macroscopic quantities

Answer 1

Independent of the size of the system. E.g. pressure temperature tension

Question 2

System

Answer 2

Portion of the universe with a certain measurable quantities (E.g. pressure and volume) which define its equilibrium state

Question 3

Surroundings

Answer 3

The rest of the universe outside the system

Question 4

Equilibrium state

Answer 4

No net macroscopic flow of energy or matter. State remains constant unless acted upon externally

Question 5

Macroscopic

Answer 5

Bog property is visible to the naked eye e.g. tempo, pressure, volume

Question 6

Microscopic

Answer 6

Positions and velocity is of individual molecules or atoms

Question 7

Isolated system

Answer 7

No energy and matter exchange with surroundings

Question 8

Closed system

Answer 8

No matter exchange with surroundings but can exchange energy. Has walls which allows the transfer of thermal energy

Question 9

Diathermal

Answer 9

Heat can pass through

Question 10

Adiabatic

Answer 10

No heat can pass through

Question 11

First law of thermodynamics

Answer 11

Change in internal energy equals work done plus heat transferred

Question 12

Entropy

Answer 12

A measure of a systems disorder. Quantifies the number of microscopic configurations with given macroscopic quantities

Question 13

Which way does heat flow

Answer 13

Heat will always flow from hot to cold unless something forces it

Question 14

Zeroth law of thermodynamics

Answer 14

If system A is initially and thermal equilibrium with system B and B is in thermal equilibrium with C then A must be in thermal equilibrium with C

Question 15

Macroscopic variables at thermal equalibrium

Answer 15

Remain constant once thermal equilibrium is reached

Question 16

Extensive macroscopic quantities

Answer 16

Proportional to the size of the system. E.g. volume, length, number of gas molecules

Question 17

Equilibrium states and state variables

Answer 17

Equilibrium states are defined by pairs of conjugate state of variables, one extensive one intensive and the product always has the dimensions of energy

Question 18

Functions of state

Answer 18

Any quantity which takes a unique value for an equilibrium state of the system. Eg energy, temp, pressure, volume, energy.

Depends only on current state not how it is formed

Question 19

Ideal gas

Answer 19

One where atoms/molecules are point like (no size or shape) and noninteracting (no forces exerted on each other)

Question 20

Isotherm

Answer 20

A curve on a PV diagram for an isothermal process

Question 21

Isotherm behaviour

Answer 21

At high temperatures isotherms behave similar to an ideal gas

Question 22

Resistance thermometer

Answer 22

use the electrical resistance of an ideal metal, such as platinum or copper. They’re accurate over a large range but not good at the low end

Question 23

Gas thermometer

Answer 23

Use a fixed quantity of gas held within a container with a fixed volume. Not very practical but accurate and operate over a large range of temperatures

Question 24

Constant volume thermometer

Answer 24

Difficult to use but accurate over a wide range so more accurate predictor of temperatures at both extremes

Question 25

Pyrometer

Answer 25

Used for black bodies. Ideal at high temps (100‘s of degrees) can go down to room temp but useless below that. Relationship with temp is non linear so requires careful calibration

Question 26

Thermocouples

Answer 26

Measure potential difference at a junction of two metals (typically 10’s of micro volts per kelvin). Dependence on temp not very linear. Very narrow temp range