What is the minimum work needed to push a 950-kg car 310 m up a 9.0oincline?(adsbygoogle = window.adsbygoogle || []).push({});

a) ignore friction,

b) assume the effective coefficient of friction is 0.25

a)

Fnet=mg sin =(950 kg) (9.8 m/s2)(sin 9°)= 1456 N

W=Fd

W=(1456 N)(310 m)= 451,360 J

b)

Fnet=mg sin - µ mg cos

Fnet=(950 kg) (9.8 m/s2)(sin 9°)- (0.25)(950 kg) (9.8 m/s2)(cos 9°)=

Fnet=1456 N-2299 N=-843 N

W=Fd

W=(-843 N)(310 m)= -261330 J Should this be negative?

In a rope climb, a 70-kg athlete climbs a vertical distance of 5.0 m in 9.0 s. What minimum power output was used to accomplish this?

New to power problems? How should I set this up?

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# Homework Help: Friction and Power Problem

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