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## Homework Statement

a block of mass m = 20 kg is placed on the floor of a lift (mass M = 1000 kg), the lift is being pulled up distance d =25m by a cable, the normal force on the block F

_{N}has a constant magnitude of 300N, how much work is done on the lift by the force on the cable?

## Homework Equations

W

_{gravity}= -mgd m=mass, d = distance, g= 9.8

W = Fd

W

_{net}= [tex]\sum Work[/tex]

## The Attempt at a Solution

For Normal force I used W = Fd >> 300N x 25m = 7500J

For W

_{gravity}I did >> -(20+1000) x 9.8 x 25 = -249900 J

Then W

_{net}= -W

_{gravity}+ W = -249900 + 7500 = -242400 J or -242.4 KJ

for some reason I don't think this is right? can anybody give me any advice please? I have not been provided with the actual answers.