A rupee coin, starting from rest rolls down a distance of 1 m on a plane inclined at an angle of `30^(@)` with the horizontal. Assuming that `g=9.81 ms^(-2)`, time taken is : -

Options

A. 0.32 s
B. 0.48 s
C. 0.782 s
D. 1.0 s

Answer

C

Explanation

`t=(1)/(sin theta) sqrt(beta.(2h)/(g))`
`=(1)/(sin theta) sqrt((1+(1)/(MR^(2))) (2 s sin theta)/(g))`
`or t=sqrt((2s(M+(I)/(R^(2))))/(Mgsin theta))`
for disc : `I=(1)/(2) MR^(2)`
`therefore t=sqrt((2s xx (3M)/(2))/(Mg sin theta))=sqrt((3s)/(g sin theta))`
`=sqrt((3xx1)/(9.8xx sin 30^(@)))=0.782` sec.