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a thermodynamic system is taken from the state i to statef along the path iaf. It is found that the heat absorbed by the system is 40 cal and work done by the system is 16.19 cal. Along the path i bf, the heat absorbed is 35 cal. (a) Find the work done along the path i bf. (b) If W = - 10 cal for the curved return path fi, what is for this path ?(c) Take U_(b) = 20 cal, what is U _(f)? (d) If U _(b) = 20cal, what is for the process ib?

Answer» <html><body><p></p>Solution :`1 cal = 4.2` Joule <br/> First law of thermodynamilcs is `Delta U = Q - <a href="https://interviewquestions.tuteehub.com/tag/w-729065" style="font-weight:bold;" target="_blank" title="Click to know more about W">W</a> = U _(f ) - U _(i)` <br/> `Q = ( U _(f) - U _(f)) + W` <br/> ` Q = 40 cal = 40 xx 4.2` <br/> `= 168 J` <br/> `W = 16.19 cal` <br/> `= 16. 19 xx 4.2 = 68 J` <br/> `U _(f) - U _(i) = Q - W` <br/> `= 168 - 68 = 100 J` <br/> The <a href="https://interviewquestions.tuteehub.com/tag/change-913808" style="font-weight:bold;" target="_blank" title="Click to know more about CHANGE">CHANGE</a> in internal <a href="https://interviewquestions.tuteehub.com/tag/energy-15288" style="font-weight:bold;" target="_blank" title="Click to know more about ENERGY">ENERGY</a> between i and f is 100 J, and is independent of the path followed, because U is a point function and not a path function <br/> (a) Work done along the path i b f ` W = Q - Delta U` <br/> `Q = 35 xx 4.2=147 - 100 = 47 J` <br/> (b) For the path `fi, Q = ? W =- 10 cal =- <a href="https://interviewquestions.tuteehub.com/tag/42-316129" style="font-weight:bold;" target="_blank" title="Click to know more about 42">42</a> J` <br/> `Q = W + ( U_(i)U _(f)) = W - (U _(f) - U _(i)) =0 42 -100 = 0 142 J` <br/> (c ) `U _(i) = 8 cal = 8 xx 4.2 = 33.<a href="https://interviewquestions.tuteehub.com/tag/6-327005" style="font-weight:bold;" target="_blank" title="Click to know more about 6">6</a> J U _(f) = ?` <br/> `U _(f) - U _(i) = 100 J` <br/> (d) `U _(b) = 20 cal = 20 xx 33.6 = 133. 6 J` <br/> `U _(i) = 8 cal = 8 xx 4.2 = 33. 6 J` <br/> `DeltaU = U _(b) - U _(i) = 84 - 33. 6 = 50.4 J` <br/> The work done for the path ib is same as that for i b f so <br/> `W = 47 J `from (a) <br/> `Q = DeltaU + W = 50.4 + 47 = 97.4 J`</body></html>


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