A uniform cable of mass M and length L is placed on a horizontal surface such that its 1/nth part is hanging below the edge of the surface. To lift the hanging part of the cable upto the surface, the work done should be:
MgL/n2
nMgL
MgL2/n2
2MgL/n2
Solution:
Correct option is B. MgL/2n2 Mass of the hanging part = M/n COM = L/2n Work done W = mghCOM = (M/n)g(L/2n) = MgL/2n2