A block slides down an incline of `30^(@)` with the horizontal starting from rest it covers `8m` in the first two seconds Find the coefficient of kinetic friction between the two .

Answer

`0.11`

Explanation

Here, `theta = 30^(@), u = 0, s = 8 m, t = 2s`
From `s = y t+ (1)/(2)a t^(2)`
`8 = 0 + (1)/(2) xx a (2)^(2)` or `a = 4 ms^(-2)`
As `a = g (sin theta - mu cos theta)`
`:. 4 = 9.8 (sin 30^(@) - mu cos 30^(@))`
`= 9.8 ((1)/(2) - mu sqrt3/(2))`
`mu = (0.9)/(4.9 sqrt 3)=0.11` .