3.1 Work, heat & First Law of Thermodynamics

Question 1

What is the Work Kinetic Energy Theorem

Answer 1

ΔK = Wc + Wdiss + Wext

Wconservative: independent of path
Wdissipative: friction-like dissipation. path IMPORTANT
Wext: Work by external forces

Question 2

Translate the Work Kinetic Energy Theorem, and write it in terms of External Work, and the 3 Different types of Energies

Answer 2

Wc = -ΔU potential energy
Wdiss = -ΔEth

Wext = ΔK + ΔU + ΔEth

Question 3

What equation models the Work done on an Ideal Gas

Answer 3

W = -∫pdV

☆Pressure is not a constant

Question 4

Describe the sign of Work when a gas expands vs contracts

Answer 4

• Expands, Work negative
• Contracts, Work positive

(When contracting, work is being done TO the gas)

Question 5

Describe…
Isochoric Process
Isobaric Process
Isothermal Process

Answer 5

khora: “space” Volume is constant
W = 0

bar: “pressure” Pressure is constant
W = -PΔV

therme “heat” Temperature is constant
W = -∫pdV