Hi, great job. I just want to check one thing. at about 10mins, when he was talking about heat input (Q) = q1, where is q2? why it has not been taken into consideration? otherwise, excellent video for us to learn the concept.
By convention, heat or work flowing into the system will be positive. In general, when you talk about q or w in thermodynamics with this convention, you are basicly only talking about the flow into the system. Now, with this convention, a heat flow out, designated by arrow leaving, will have q negative because heat is flowing out, and then -q will be positive. The "-" is there because the arrow is leaving the system;"-"means out in this case. It's for the heat balance around the engine: In-Out.
sign convention is really confusing......
naveenthumu8 3 months ago
He sound just like Christopher Walken !
gomunkul 11 months ago
:O thats what i call high quality (Y)
Andre1a 1 year ago
can somebody explain were he say W irrev is greater than W rev at 44:32
moyamba5 2 years ago
Hi, great job. I just want to check one thing. at about 10mins, when he was talking about heat input (Q) = q1, where is q2? why it has not been taken into consideration? otherwise, excellent video for us to learn the concept.
panumbang 2 years ago
@PointOnACurve
FYI
By convention in thermodynamics, Work in is, -W, and Work out is +W. Where as, Heat in is , +Q and Heat out is -Q.
Thus the First Law equation gives;
Q - W = change in U.
Where U is the internal energy.
nolaeast 2 years ago
By convention, heat or work flowing into the system will be positive. In general, when you talk about q or w in thermodynamics with this convention, you are basicly only talking about the flow into the system. Now, with this convention, a heat flow out, designated by arrow leaving, will have q negative because heat is flowing out, and then -q will be positive. The "-" is there because the arrow is leaving the system;"-"means out in this case. It's for the heat balance around the engine: In-Out.
PointOnACurve 2 years ago
q2 is entering the cold reservoir thus its negative.
s27448632 2 years ago
He confuses me with the sign convention! -q2 is positive kind of thing. What is this?
saiyeek 2 years ago