The question is basically, a block with a mass "m" is sliding up and down on a incline plane with an angle of inclination that is β. The leaving velocity (Start velocity v_i) is v0 and the frictionskoefficient is between the plane and the block is μ. Determine the velocity "v" when the block has returned to its starting position. -μ*mg cos β - mg sin β=m*a (-μ*mg cos β - mg sin β)/m=a -v=v0+at, , however, know v and t is unknown, how i find any of them? v0 is= v0 and a is what i wrote. Any tips ? And have i done right so far?