Question

A metallic chain 1m long lies on a horizontal surface of a table. the chain starts sliding on the table if 25 cm (or more of it) hangs over the edge of a table. the correct value of the coefficient of friction between the table and the chain is

Answer 1

let m be the mass for 1 m length chain then 25 cm length the mass would be: = > m/4
balacncing the forces we get,
f = mg/4.
u*(3m/4)*g = mg/4
u= 1/3
Hope it helps!!

Answer 2

mass of 100 cm chain = m
therefore,
mass of 25 cm chain = m/4
and mass of remaining chain (75 cm) = 3m/4
now,
f = mg
i.e. u(mue) x (3m/4) x g = (m/4) x g ( g is cancelled out)
therefore, we get ,
u (mue) = 1/3.