A-LEVEL PHYSICS: 11.2.3: Thermodynamic Processes (SaveMyExams)

Question 1

the 4 main thermodynamic processes are:

Answer 1

-isovolumetric (W=0)

-isobaric (∆p=0)

-isothermal (∆T=0)

-adiabatic (∆Q=0)

Question 2

isobaric process:

Answer 2

a process in which no change in pressure occurs
(constant pressure)

Question 3

constant pressure process:

Answer 3

isobaric process

Question 4

when do isobaric processes occur?

Answer 4

when gases expand or contract at constant pressure during a change in temperature (Δp=0)

Question 5

when there is a change in volume at a constant pressure, work done = …

Answer 5

W=p∆V

Question 6

first law of thermodynamics:

Answer 6

∆U=Q-W

Question 7

isovolumetric process:

Answer 7

a process where no change in volume occurs and the system does no work
(constant volume ∆V=0 ∴ W=0)

Question 8

process where no change in volume occurs and the system does no work:

Answer 8

isovolumetric

Question 9

a process in which no change in pressure occurs (constant pressure):

Answer 9

isobaric

Question 10

if there is no change in volume, then there is no ___ ___ on or by the ___, so…

Answer 10

work done, gas, W=0

Question 11

first law of thermodynamics in isobaric process:

Answer 11

∆U= Q ± (p∆V)

(W=p∆V)

(± whether work has been done on or by the gas as a result of ∆V) (expansion = +∆V) (compression = -∆V)

Question 12

first law of thermodynamics in isovolumetric process:

Answer 12

∆U = Q

(bc W=0 in isovolumetric processes)

Question 13

isothermal process:

Answer 13

a process in which no change in temperature occurs (constant temperature)

Question 14

a process in which no change in temperature occurs (constant temperature):

Answer 14

isothermal

Question 15

first law of thermodynamics in isothermal process:

Answer 15

Q=W

(if the temperature does not change, then the internal energy of the gas will not change ∴ ∆U=0)

Question 16

adiabatic process:

Answer 16

a process where no heat is transferred into or out of the system (Q=0)

Question 17

a process where no heat is transferred into or out of the system (Q=0)

Answer 17

adiabatic

Question 18

first law of thermodynamics in adiabatic process:

Answer 18

∆U = -W

(bc Q=0)

Question 19

state and explain first law of thermodynamics in adiabatic process: (3)

Answer 19

∆U = -W

-because Q=0 (no heat is transferred into or out of the system)

-this means that all the work done is at the expense of the system’s internal energy

• ∴ an adiabatic process will usually be accompanied by a change in temperature (due to ∆U)

Question 20

adiabatic processes in ideal gases can be modelled by the equation:

Answer 20

pV ^γ = constant