Efficiency and Temperature in Heat Engine Cycles: Approaching Parts B, C, and D

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The discussion focuses on challenges faced in parts B, C, and D of a heat engine cycle problem after successfully completing part A. The efficiency formula for a heat engine, e = work done by engine/qh, is considered but the user is uncertain about its application. There is confusion regarding how to determine the cold reservoir temperature (Tc) without knowing the hot reservoir temperature (Th). The user expresses a hunch about a potential answer for part D but lacks a solid explanation. Guidance is requested to clarify these concepts and assist with the problem-solving process.
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Homework Statement
Need help with b,c,d.
Relevant Equations
Wnet/QH
e-carnot = 1-(Tc/Th)
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I didn't have much trouble with part a but I'm struggling with b,c, and d. I considered the efficiency formula for a heat engine e = work done by engine/ qh
but i am unsure of how to approach it.
for part c) not sure how i can get to Tc without knowing Th
for d) my gut is telling me 5/2 but i have no explanation for that. Any guidance/help is appreciated
 
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Let's see what you've done so far in part (b).
 
Thread 'Chain falling out of a horizontal tube onto a table'

Thread 'Chain falling out of a horizontal tube onto a table'

My attempt: Initial total M.E = PE of hanging part + PE of part of chain in the tube. I've considered the table as to be at zero of PE. PE of hanging part = ##\frac{1}{2} \frac{m}{l}gh^{2}##. PE of part in the tube = ##\frac{m}{l}(l - h)gh##. Final ME = ##\frac{1}{2}\frac{m}{l}gh^{2}## + ##\frac{1}{2}\frac{m}{l}hv^{2}##. Since Initial ME = Final ME. Therefore, ##\frac{1}{2}\frac{m}{l}hv^{2}## = ##\frac{m}{l}(l-h)gh##. Solving this gives: ## v = \sqrt{2g(l-h)}##. But the answer in the book...
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