A 3.50 kN piano is lifted by 3 workers at constant speed to an apartment 25 m above ground. Each worker is able to deliver 165 W of power and the pulley is 75% efficient (25% lost due to friction on pulley). Neglecting mass of pulley, what is the time required to lift the piano from the street to the apartment.(adsbygoogle = window.adsbygoogle || []).push({});

I know that F=T-mg=ma=0

T=3500N

Work=3*165=495W=F/t

But I'm not really sure how to sort this problem out and incorporate the 75% efficiency of the pulley and the height above ground. Please help me.

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# Homework Help: Help please, power (piano pulled up by workers through pulley)

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