Exam2 Flashcards
What is the boundary work (Wb) for constant volume
Wb=0
What does the conservation of energy equation simplify to regarding energy analysis of closed systems
Q+W=delta E
What is one type of work possible in a closed system
Boundary work
Is expansion considered (+) or (-) and why
(-) since its work out
Is compression considered (+) or (-) and why
(+) since its work in
What is the general equation for boundary work(Wb)
Wb= the integral of pressure with respect to volume (PdV) from state 1 to state 2
What is another way a problem will inform you that it’s constant volume
Rigid tank and isometric
How do you calculate boundary work(Wb) for constant pressure
Wb=PdeltaV, Wb=pressure times the change in volume from state 1 to state 2
What is another way a problem might inform you that it’s constant pressure
Isobaric, weighted piston, piston not attached to shaft
How do you calculate boundary work for a isothermal compression of an ideal gas
Wb= PVln(V2/V1)
What is the difference between big V and little v
Big V represents volume, little v represents specific volume
How do you calculate boundary work (Wb) for a polyatomic process (PV^n)
Wb= (P2V2-P1V1)/(1-n) and n cannot equal 1
How do you calculate boundary work of an ideal gas polyatomic process
(MR(T2-T1)/(1-n))
How do you calculate boundary work (Wb) by a spring piston
Wb= ((P1+P2)/2)(V2-V1)
What is the equation for energy balance for a closed system
Ein-Eout=change in energy (delta E)
