Starting from rest a body slides down a `45^(@)` inclined plane in twice the time it takes to slide down the same distance in the absence of friction. The coefficient of the body and the inclined plane is :

Options

A. 0.2
B. 0.25
C. 0.75
D. 0.5

Answer

C

Explanation

( c) `s=(1)/(2)at^(2) " or " t=sqrt((2s)/(a)) " or " t prop (1)/(sqrt(a))`
`(t_(1))/(t_(2))=sqrt((a_(2))/(a_(1)))`
or `" " 2=sqrt((g sin theta)/(g sin theta-mug cos theta))=sqrt((1)/(1-mu))`
as`" " sin 45^(@)=cos 45^(@)`
`therefore" " 1- mu =(1)/(4) implies mu=0.75`