A mass of 2 kg is whirled in a horizontal circle by means of a string at an initial speed of 5 revolutions per minute. Keeping the radius constant the tension in the string is doubled. The new speed is nearly
7 rpm
Tension in the string T=mω2r=4π2 n2 mr
∴ T∝n2 ⇒n2n1=√T2T1⇒n2=5√2TT=7 rpm