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Railways NTPC (Technical Ability) Thermodynamics Question Bank Thermodynamics

  • question_answer
    A heat engine using lake water at \[12{}^\circ C\] as source and the surrounding atmosphere at \[2{}^\circ C\] as sink executes 1080 cycles per minute. If amount of heat supplied per cycle is 57 J, what is the output of the engine?

    A) 66 W                

    B) 56 W

    C) 46 W                

    D) 36 W     

    Correct Answer: D

    Solution :

    \[{{T}_{1}}=273+12=285\,K,\]   \[{{T}_{2}}=273+2=275\,K\] \[{{Q}_{1}}=57\,\,\text{J/cycle}\,\,\text{=}\,\,\text{57}\times \,\frac{1080}{60}=1026\,\,W\] \[\eta =1-\frac{{{T}_{2}}}{{{T}_{1}}}=1-\frac{275}{285}=0.035=\frac{W}{{{Q}_{1}}}\] \[W=1026\times 0.025=36\,\,W\]


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