1. The problem statement, all variables and given/known data An object passes through point P0 in the instant t=0, going up with a velocity v0=3m/s along a tilted rough surface (dynamic friction coefficient µd=0.3) which forms an angle α=30° with the "ground". The length L of the slanted surface is practically endless. Find a)h, the maximum height the object can reach b)vf, the final velocity when the object re-passes through point P0 assuming that the static friction coefficient, µs, is such that the object doesn't stop when it reaches the maximum height. Note: This problem can be solved either by applying the 2nd dynamics principle or through energetic deductions. [Answers: a) h=30 cm ; b) vf=1.69 m/s] 2. Relevant equations K(B)+U(B)= K(A)+ U(A) (kinetic energy and potential energy) F=µ∙N (friction force, a non-conservative force) W=⌠F∙ds (work as integral of force and movement) 3. The attempt at a solution I tried to solve the first question, find h , through the conservation of mechanical energy. I called B the point of max height, A=P0 the starting point. E(B)=E(A) - Work(A→B) ½m∙v²(B)+mgh=½m∙v²(A) - F∙L where F is the friction force, a non-conservative force: F=µd∙N=µd∙(mg∙cos(30°)). But now how do I continue? L is ∞, and I don't know v(B). should I assume v(B)=0 in order to solve the 1st question? Is what I have done till this point, right? the picture of this problem is a bit confusing so I'm sending you a copy just as it is on the paper.