A stone tied to the end of a string 80 cm long is whirled in a horizontal circle with a constant speed . If the stone makes 14 revo-lutions is 25 s, what is the magnitude and direction of acceleration of the stone ?

Explanation

Given radius `=80 cm =0.80 m, v=(14)/(25)//s `
`therefore omega =2 pi v =2 xx(22)/(7) xx(14)/(25)`
`=(88)/(25) "radius" s^(-1)`
As centripetal acceleration `=romega^(2)`
`=0.8xx((88)/(25))^(2)=9.9 ms^(-2)`
The centripetal acceleration acts along the radius , towards the centre of the circle .