A stone tied to the end of a 20 cm long string is whriled in a horizontal ciecle with a constant angular speed .If the centripetal acceleration is `980 cm//s^(2)`, its angular speed is .

Options

A. `7 rad//s`
B. `14 rad//s`
C. `pi rad//s`
D. `20 rad//s`

Answer

A

Explanation

`a=r omega ^(2) " " therefore omega ^(2)=(a)/(r)`
`=(980)/(20)=49`
`therefore omega =7 rad//s`.