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retracell
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Homework Statement
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.
Homework Equations
d1=d0+v0t+1/2at2
Fnet=ma
W=FDcos[tex]\theta[/tex]
[tex]\epsilon[/tex]=Eoutput/Einputx100%
The Attempt at a Solution
d1=d0+v0t+1/2at2
30=0+0+1/2(152)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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