Question

A heavy uniform chain lies on a horizontal table top. If the co efficient of friction between the chain and the table surface is 0.25 , then the maximum fraction of the length of the chain that can hang over one edge of the table is

• A. 20%
• B. 25%
• C. 35%
• D. 15%

Answer 1

The correct option is A

20%

Chain has a mass ‘m’ and length ‘l’. Let a maximum length x of the chain project over the table. The length of the chain on the table is L – x. Then the pulling force due to the length x should be balanced by the limiting friction acting to the left.

$\frac{m}{l}\times g=\mu \frac{m}{l}(l–x)g$

$x=\frac{\mu l}{1+\mu }$

= $\frac{0.25}{1.25}$

= 0.2

Therefore it is 20%