Thermodynamics 2 - The First Law

[snowman78619]

E = Q - W (for work done by the gas)

E = Q + W (for work done on the gas)

[dannyze85]

thank you buddy!!!

[marivicmakkoy]

nice.....one....... sample problem pls......

[godfilh]

also the more heat the more energy we can get



[godfilh]

so it means that i can get energy from heat or not

[ithapaa]

oh thanks so much..that helped a lot!!!

good concept...

[nikan4now]

Nice video Just one thing, in the collision of the non-elastic particles you said "the energy is not conserved" which I believe should've been stated as "the mechanical energy is not conserved" since as you pointed earlier energy is always conserved.

[ithapaa]

but i thought E=q+w not q-w.....

this is confusing to me.. but good work though in explaining other things...

[jcquintos]

i used to get confused too,, but the signs of w is convention dependet... my physics thermodynamics class use -w, my chem engg thermodynamics use +w.. (imagine studying for exams with two different conventions.. haha)... for -w, the work considered is work done by the system, and since it's doing work, it loses some internal energy,, thus the negative sign..

[jcquintos]

. the +w considers work done by an external force (surroundings)... it's formula is -∫PdV... so it's just like the negative sign is nested in the formula itself....

an expanding system means positive work done by the system, and from the first law, this (+)quantity is subtracted from Q.

an expanding system also means negative work done by the surroundings , this (-)quantity is added to Q..

hope that helps

[TharunyaGanesan]

@ithapaa  Yeah E=q+w..Is it wrong.??

[PartzAct]

Good job on explaining. =)