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

A 11.0 kg crate is pulled up a rough incline with an initial speed of 1.3 m/s. The pulling

force is 121.0 N parallel to the incline, which makes an angle of 12.6◦ with the horizontal.

The coefficient of kinetic friction is 0.31 and the crate is pulled a distance of 8.0 m.

The acceleration of gravity is 9.81 m/s^2 .

2. Relevant equations

a) Find the work done by Earth’s gravity

on the crate. Answer in units of J.

3. The attempt at a solution

Fnormal=m*g*costheta

Fnormal=105.3111778N

Fnormal* coefficient of friction=Ffriction

Ffriction=32.64646511N

Fapplied-Ffriction=Fnet

Fnet=88.35353489N

Work=N*m

Work=706.8282791N*m

-(Work*sin12.6)=W done by gravity

Work done by gravity is 154.1898119N*m

I think I did it right, but the computer marked me wrong. Can anyone explained this?

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# Homework Help: Work done by gravity on a object on an inclined plane

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