Question

A thin rod of mass m elongates by l when a body of mass m is suspended from it the work done is


​

Answer 1

Answer:

If these are your options:

mgl

mgl/2

2mgl

zero

Explanation:

Let initial length of the rod be L

Then final length of the rod will be L+l

Initial distance of COG of rod from the bottom =  

2

L

Final distance of COG of rod from the bottom =  

2

L+l

Displacement of the COG of the rod =  

2

L+l

​  

 −  

2

L

​  

  =  

2

l

Work done =F.s=mg  

2

l

Hence correct answer is option B