Option B - Thermodynamics

Year 13 SL Physics

Thermodynamics

• System – Environment of activity• Surroundings – Factors impacting the system• Boundary (wall) – System barriers

Work on a System

• Work done on a system or energy transferred to the system because of temperature differences result in the internal energy of that system increasing

• No change in state– Increase in Kinetic Energy

• Change in State– Increase in potential energy

Internal Energy

• Total Internal Energy of a System = – Total Potential Energy + Random Kinetic Energy of

all particles

Ideal Gas

• Internal Energy is all kinetic

0th Law of Thermodynamics

1st Law of Thermodynamics

• Changes to Internal Energy– Doing work on the system• Allowing the system to do work on the surroundings

– Transferring energy to or from the system as a result of a difference in temperature

Q = ΔU + W

Types of Work Done

• Isobaric Changes– Constant Pressure

• Isothermal Changes– Constant Temperature

• Adiabatic Changes– Constant Energy

• Isovolumetric Changes– Constant Volume

Isobaric Changes

• Pressure is constant• Q = ΔU + pΔV• W is positive = expands• W is negative = compressed

Isobaric Changes

Isothermal Changes

• Temperature is constant– So internal energy of the system remains constant

• Q = W– Where W = pΔV

Isothermal Change

Adiabatic Changes

• Constant Energy– No energy is

transferred• Usually contains

a well insulated barrier between the system and surroundings

Isovolumetric Changes

• Constant volume– So no work done

• Q = ΔU

2nd Law of Thermodynamics

• It is impossible to transfer energy from a body at a lower temperature to one at higher temperature without doing work on the system

• It is impossible to extract energy from a hot reservoir and transfer this entirely into work.

• Law of Entropy

Entropy• All materials move towards

disorder

• ΔS = measurement of entropy

• ΔQ = energy absorbed by the system

• T = temperature in Kelvin

• We will do some examples and practice problems on Friday. But please learn these terms – That means you will need to study them Hubert