A chain of mass M is placed on a smooth table with 1/n of its length L...
Given: Mass of chain = M, Length of chain = L, Portion of chain hanging over the edge = 1/n*L
To find: Work done in pulling the hanging portion of the chain back to the surface of the table
Assumptions: The table is smooth, i.e., there is no friction between the chain and the table.
Solution:
1. Finding the center of mass of the chain:
- The center of mass of the chain will be at a distance of 1/2*L from the end of the chain that is resting on the table.
- Therefore, the distance between the center of mass of the chain and the point where the hanging portion of the chain touches the table is (1/2 - 1/n)*L.
2. Finding the potential energy of the hanging portion of the chain:
- The potential energy of the hanging portion of the chain is given by mgh, where m is the mass of the hanging portion, g is the acceleration due to gravity, and h is the height to which the hanging portion is lifted.
- Here, m = M*(1/n), g = g, and h = (1/n)*L.
- Therefore, the potential energy of the hanging portion of the chain is (MgL/n^2)/2.
3. Finding the work done in pulling the hanging portion of the chain back to the surface of the table:
- The work done in pulling the hanging portion of the chain back to the surface of the table is equal to the change in potential energy of the hanging portion of the chain.
- Therefore, the work done is (MgL/n^2)/2.
Hence, the correct answer is option 'D' - MgL/2n^2.
To make sure you are not studying endlessly, EduRev has designed JEE study material, with Structured Courses, Videos, & Test Series. Plus get personalized analysis, doubt solving and improvement plans to achieve a great score in JEE.