(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

An elevator motor which is 60% efficient uses 80kW of power while lifting a 2000kg elevator 30m. If the elevator contains five passengers of the same mass and it takes 15 seconds to accomplish this task, then determine the mass of each passenger.

2. Relevant equations

d_{1}=d_{0}+v_{0}t+1/2at^{2}

F_{net}=ma

W=FDcos[tex]\theta[/tex]

[tex]\epsilon[/tex]=E_{output}/E_{input}x100%

3. The attempt at a solution

d_{1}=d_{0}+v_{0}t+1/2at^{2}

30=0+0+1/2(15^{2})a

30=112.5a

a=0.2666666

Let x rep. each individual mass

Fapplied-mg=ma

F=(2000+5x)(0.26666)+(2000+5x)(9.8)

F=(2000+5x)(10.06666)

W=(2000+5x)(10.06666)(30)(1)

W=(2000+5x)(301.9996)

W=603999.2+1509.998x

P=(603999.2+1509.998x)/15

P=40266.61333+100.6665333x

0.6=40266.61333+100.6665333x/80000

0.6(80000)=40266.61333+100.6665333x

7733.38667=100.6665333x

x=76.822kg

Is this correct?

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# Homework Help: Elevator and unknown passenger mass

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