A 5kg block slides down a plane inclined at `30^(@)` to the horizontal. Find
(a) The acceleration of the block if the plane is frictionless
(b) The acceleration if the coefficient of kinetic friciton is 0.2

Explanation

(a) If plane is smooth.
`mg sin 30^(@)=ma`
`a=g sin 30^(@)`
`=g//2=4.9m//s^(2)`

(b) `N=mg cos 30^(@)`
`mg sin 30^(@)-mu_(k)N=ma`
`a=g sin 30^(@)-mu_(k)g cos 30^(@)`
`a=3.20m//s^(2)`