Question

A block of mass M is situated on a smooth horizontal table. A thread tied to the block passes through a hole in the table and carries a mass m at its other end. If the length of thread above the table is l and M is revolving in horizontal circle with angular speed ω on the table, then value of m so that it remains suspended at a constant height h is –

• A. Mghω²
• B. mglω²
• C. Mlω²/g
• D. Mlω²

Answer 1

Answer: (C)

Mlω²/g

Answer 2

The centripetal force is provided by the hanging weight i.e., Mlω² = mg

or m = $\frac { \mathrm { Ml } \omega ^ { 2 } } { \mathrm {~g} }$