1. The problem statement, all variables and given/known data The shape of the arch is defined by a sine function with a = 0.2 and the width of the arch is 1m. The velocity v is constant at 2m/s. What is the velocity at point P when x=0.25m? 3. The attempt at a solution So since v is just in the x-direction, I figured that's the vx speed. Then I came to having to find an equation to vy and this is where I get stuck. I remember from high school physics that equation of velocity can be essentially found by taking a derivative of the position equation. In this case I get: vy=y'=0.2*pi*cos(pi*x) From which I can find that at x=0.25m, vy = 0.444288 m/s But that combined with the horizontal speed of 2m/s gives me a resultant velocity of 2.05ish, instead of 2.19 that I'm supposed to get. Help please?