Thermodynamics

Question 1

temperature

Answer 1

measure of the average kinetic energy of the molecules of a substance

Question 2

heat

Answer 2

energy transferred across system boundary due to a temperature difference between system and surroundings

Question 3

thermal equilibrium

Answer 3

two objects will not exchange energy by heat or electromagnetic radiation if placed in thermal contact

Question 4

heat capacity

Answer 4

amount of energy needed to raise temperature by 1oC

Question 5

specific heat

Answer 5

heat capacity per unit mass

Question 6

latent heat of fusion

Answer 6

phase change from solid to liquid

Question 7

latent heat of vaporisation

Answer 7

phase change from liquid to gas

Question 8

Zeroth Law of Thermodynamics

Answer 8

If objects A and B are in thermal equilibrium with a third object C, then A and B are in thermal equilibrium with each other

Question 9

convection

Answer 9

movement of material in liquids and gases

Question 10

conduction

Answer 10

solids: contact between hot and cold regions

Question 11

radiation

Answer 11

no contact: energy transferred from hot to cold through electromagnetic waves

Question 12

ideal absorber

Answer 12

object that absorbs all energy incident on it - black body - also ideal radiator

Question 13

ideal reflector

Answer 13

absorbs none of the energy incident on it

Question 14

Adiabatic Process

Answer 14

no heat transfer between system and surroundings

Question 15

Isovolumetric Process

Answer 15

constant volume - no work done

Question 16

Isothermal Process

Answer 16

constant temperature - no change in internal energy

Question 17

Isobaric Process

Answer 17

constant pressure

Question 18

Cyclic Process

Answer 18

start and end in same state - no change in internal energy

Question 19

Entropy

Answer 19

measure of disorder - state variable, independent of path taken - which direction a process should go

Question 20

Second Law of Thermodynamics

Answer 20

process in a closed system: entropy increases for irreversible processes, remains constant for reversible - S>=0

Question 21

Reversible process

Answer 21

no dissipative effects or energy losses - every point along some path is an equilibrium state: system can be returned to original state along same path

Question 22

Irreversible process

Answer 22

all natural processes

Question 23

Heat Death of the Universe

Answer 23

entropy of universe will be maximised - all processes will cease

Question 24

Heat Engine

Answer 24

carries some substance through a cyclic process, during which the working substance absorbs energy by heat from a high temp. reservoir, work is done by the engine, energy expelled by heat to a lower temp. reservoir

Question 25

Carnot Cycle

Answer 25

heat engine operating in ideal, reversible cycle: most efficient engine possible

Question 26

Carnot’s Theorem

Answer 26

no engine can be more efficient than a Carnot engine operating between the same two reservoirs