Suppose you have a teleski to climb a skiway of d=600m and θ=15º respect horizontal and μ(adsbygoogle = window.adsbygoogle || []).push({}); _{k}=0.06 is kinetic friction coefficient in the cable. 80 skiers of 75kg (m=6000kg in total) each one wants to climb at the top at v=2.5m/s constant, What's the power that engine must provide in order to maintain this speed with that charge of skiers? Answer: 350KW

I have used: W_{external forces}=ΔE_{mechanic}+ΔE_{thermic}+ΔE_{chemical}=0, where ΔE_{mechanic}=(m*(vf)^{2}/2)+m*g*(hf)-(m*(vo)^{2}/2)-m*g*(ho)=m*g*(hf), since vf=vo y ho=0, and ΔE_{thermic}=f_{k}*d=μ_{k}*m*g*d*cos(θ), and ΔE_{chemical}is engine's energy to get the power, then:

P=-dE_{chemical}/dt

and -dE_{chemical}/dt=dE_{mechanic}/dt+dE_{thermic}/dt, hence:

P=m*g*v*(sin(θ)+μ_{k}*cos(θ))

P=46.61KW

This is not the answer, why?, please guide me and tell me what's the mistake.

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# Homework Help: Problem with energy conservation

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