Question

A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200 N?

Answer 1

Mass of the stone, m = 0.25 kg

Radius of the circle, r = 1.5 m

Number of revolution per second,

n=40/60=2/3 rps

Angular velocity, ω =v/r= 2πn ………………….(i)
The centripetal force for the stone is provided by the tension T, in the string, i.e.,

Maximum tension in the string, T_max = 200 N

Therefore, the maximum speed of the stone is 34.64 m/s.