In a construction site a lifting machine on the ground is used to lift bricks to the $8^{ ext{th}}$ floor which is 25m high. At a time the machine can lift a 2000kg load is 1min.The power satellite to the engine of the lift is 15HP.what is the efficiency of the lifting machine?[P-1.5, IUT : 2021-22]

Question

In a construction site a lifting machine on the ground is used to lift bricks to the  $8^{	ext{th}}$ floor which is 25m high. At a time the machine can lift a 2000kg load is 1min.The power satellite to the engine of the lift is 15HP.what is the efficiency of the lifting machine?[P-1.5, IUT : 2021-22]

Accepted Answer

খ. 73%

ব্যাখ্যা: লব্ধ কার্যকর ক্ষমতা, $P_{	ext{out}} = \frac{mgh}{t} = \frac{2000 	imes 9.8 	imes 25}{60} \approx 8166.67 	ext{ W}$। মোট প্রদত্ত ক্ষমতা, $P_{	ext{in}} = 15 	ext{ HP} = 15 	imes 746 	ext{ W} = 11190 	ext{ W}$। অতএব, কর্মদক্ষতা $\eta = \frac{P_{	ext{out}}}{P_{	ext{in}}} 	imes 100\% = \frac{8166.67}{11190} 	imes 100\% \approx 72.98\% \approx 73\%$।

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