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 ?

Explanation

`v = 2pi xx 1.5 xx 40/60 = 2pi ms^(-1)`
`T = (mv^2)/(R ) = (0.25 xx 4pi^2)/(1.5) = 6.6 N`
`200 = (mv_(max)^2)/(R ) ` . Which gives `v_(max) = 35 ms^(-1)`