Q 11-05-152JEE MainJEE Main 2021 (26 Aug, Shift 1)Medium
A uniform chain of length $3$ m and mass $3$ kg overhangs a smooth table with $2$ m laying on the table. If $K$ is the kinetic energy of the chain in J as it completely slips off the table, then the value of $K$ is (Take $g = 10$ m s$^{-2}$)
Numerical value type. Enter your answer.
Answer: 40
Take the table top as the zero of potential energy.
Initially the hanging $1$ m (mass $1$ kg) has its centre $0.5$ m below: $U_i = -1\times10\times0.5 = -5$ J.
Finally the whole chain hangs with its centre $1.5$ m below: $U_f = -3\times10\times1.5 = -45$ J.
$K = U_i - U_f = 40$ J.
Solution by Sreeraj P, M.Sc Physics