A block slides from rest from the top of a plane 8m long and inclined 35o with the horizontal. If the coefficient of friction is 0.20, find how long it will take the body to reach the bottom of the plane.

3 answers

component of weight down plane
= m g sin 35

friction up plane = .2 m g cos 35

so force accelerating m down plane
= m g (sin 35 - .2 cos 35)

a = force/m = g(sin 35 - .2 cos 35)

distance =(1/2) a t^2 = 8 meters
solve for t
I see your other problems. They are really just like this one. Try them.
I still don't get it sorry