Termodinamik tizim

Termodinamikaning birinchi qonuniga doir masalalar qanday yechiladi?
1-masala: porshen ostidagi azot
Germetik berk idishdagi qoʻzgʻaluvchan porshen ostida azot gazi bor. Termodinamik jarayonda gazga 200\text{ joul}200 joul200, start text, space, j, o, u, l, end text issiqlik berildi va gaz bu jarayonda 300\text{ joul}300 joul300, start text, space, j, o, u, l, end text ish bajardi.
Ushbu jarayonda gazning ichki energiyasi qanday oʻzgargan?
Yechish:
ishni termodinamikaning birinchi qonuni formulasini yozishdan boshlaymiz.
\Delta U=Q+W \quad \text{(termodinamikaning birinchi qonunidan boshlang)}ΔU=Q+W(termodinamikaning birinchi qonunidan boshlang)delta, U, equals, Q, plus, W, start text, left parenthesis, t, e, r, m, o, d, i, n, a, m, i, k, a, n, i, n, g, space, b, i, r, i, n, c, h, i, space, q, o, n, u, n, i, d, a, n, space, b, o, s, h, l, a, n, g, right parenthesis, end text
\Delta U=(+200 \text{ J})+W \quad \text{( }Q=+200\text{ J ni keltirib qoʻyamiz)}ΔU=(+200 J)+W( Q=+200 J ni keltirib qoʻyamiz)delta, U, equals, left parenthesis, plus, 200, start text, space, J, end text, right parenthesis, plus, W, start text, left parenthesis, space, end text, Q, equals, plus, 200, start text, space, J, space, n, i, space, k, e, l, t, i, r, i, b, space, q, o, ʻ, y, a, m, i, z, right parenthesis, end text 
[Nega issiqlik miqdori musbat ishoraga ega?]
\Delta U=(+200 \text{ J})+(-300\text{ J}) \quad \text{(}W=-300\text{ J ni keltirib qoʻyamiz)}ΔU=(+200 J)+(−300 J)(W=−300 J ni keltirib qoʻyamiz)delta, U, equals, left parenthesis, plus, 200, start text, space, J, end text, right parenthesis, plus, left parenthesis, minus, 300, start text, space, J, end text, right parenthesis, start text, left parenthesis, end text, W, equals, minus, 300, start text, space, J, space, n, i, space, k, e, l, t, i, r, i, b, space, q, o, ʻ, y, a, m, i, z, right parenthesis, end text 
[Nega ish manfiy ishora bilan qoʻyildi?]
\Delta U=-100\text{ J} \quad \text{(hisoblang va nishonlang)}ΔU=−100 J(hisoblang va nishonlang)delta, U, equals, minus, 100, start text, space, J, end text, start text, left parenthesis, h, i, s, o, b, l, a, n, g, space, v, a, space, n, i, s, h, o, n, l, a, n, g, right parenthesis, end text
Yodda tuting: gazning ichki energiyasi kamaysa, uning harorati ham pasayadi.