# January 29 AP Physics Gateway High School Olycasts.

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January 29 AP Physics Gateway High School Olycasts

IN A gas follows the cycles shown. How much work is done?

Objective: To find out how the conservation of energy applies to thermodynamics

Homework check

Conservation of Energy ΔPE + ΔKE + ΔU = 0

James Prescott Joule

Work in thermodynamic processes W=FΔd W=PAΔd W= - PΔV

PV diagram

First law of Thermodynamics ΔU = Q + W

Isovolumetric (volume constant) ΔU = Q

Isothermal (temperature constant) ΔU = 0 Therefore Q = W

Isobaric (pressure constant) ΔU = Q + W

Adiabatic (thermally isolated system) ΔU = W

Processconditions first law Isobaricboth temp ΔU=Q+W and volume change Isovolumetricno workΔV=0 so W=0 so ΔU=Q Isothermalno change ΔU=Q+W=0 in T or U so Q= - W Adiabaticno energyQ=0 transfer asso ΔU=W heat

PV diagrams and thermodynamic processes (quick quiz 12.2) Identify the paths

Problems White board these problems together: 50, 51, 54

Out: Which of these processes are isothermal, isovolumetric, or adiabatic: a)A tire being rapidly inflated b)A tire expanding gradually at a constant temperature c)A steel tank of gas being heated