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 FN has a constant magnitude of 300N, how much work is done on the lift by the force on the cable?
Wgravity = -mgd m=mass, d = distance, g= 9.8
W = Fd
Wnet = [tex]\sum Work[/tex]
The Attempt at a Solution
For Normal force I used W = Fd >> 300N x 25m = 7500J
For Wgravity I did >> -(20+1000) x 9.8 x 25 = -249900 J
Then Wnet = -Wgravity + 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.