1. The problem statement, all variables and given/known data A mass slides on a frictionless plane inclined at an angle theta from the horizontal. The mass starts from rest at a height h(1)+h(2) , then slides off the ramp at height h(1). I will post the link so you can visualized the problem http://courses.ncsu.edu/py411/lec/001/ What is the velocity vector of the mass when the mass is at height h1 (as the mass leaves the ramp?) 2. Relevant equations Force equations , Mechanical Energy equations 3. The attempt at a solution I apply to methods to determined the velocity of mass : Forces equations and Mechanical Energy equations. I will start with Force equations y component: F(normal)-mg cos(theta)=0, nothing moves in y direction x-components: mg sin(theta)-0=m*a=> a=g*sin(theta) ; next thing I did was integrate a to get v and now v = gt*sin(theta). My prof said he wanted my v in vector form, meaning I think he wants the velocity , in the x, y and z directions. so v= (gt sin(theta))x + (gt cos(theta)+0 z. Now I will find the velocity the alternative way: (K(f)-K(i))+(U(f)-U(i))=0=> ((.5*m*v^2)-0)+(0-m*g*h2))=0 +> v=sqrt(2*g*h2). Both methods lead me to different velocities. What did I do wrong?