1. The problem statement, all variables and given/known data A marble of mass M and radius R is rolled up a plane of angular θ. If the initial velocity of the marble is v, what is the distance l it travels up the plane before it begins to roll back down? 2. Relevant equations 3. The attempt at a solution I would like to know the details of the motion. The answer is l≈1.3m. But I try the equation -mglsinθ=0-(1/2mv+1/2Iω), the result is about 1.5m. I know it is not the correct way, but I am just confused about the critical condition and how the friction is canceled out.