Question

A mass 2 kg describes a circle of radius 1.0 m on a smooth horizontal table at a uniform speed. It is joined to the centre of the circle by a string, which can just withstand 32 N. The greatest number of revolutions per minute the mass can make is

(A) 38 

(B) 4 

(C) 76 

(D) 16

Answer 1

Answer is (A) 38

m = 2 kg, r = 1 m, F = 32 N

Force, F = mω²r

∴ ω² = \(\frac{32}{2\times1}\) = 16

∴ ω = 4 rad/s

Frequency of revolution per minute