Here's the question: A particles position is defined by the equation x=y^2/6 and it moves at a constant velocity in the y-direction of 3 in/s. Find the velocity and acceleration when x=6 in. I know v=sqrt(vx^2+vy^2) and a is found the same way, but I have absolutely no idea how to find the velocity of in the x-direction through the equation. The only way I can think to do it is find the change in the x position over a very small interval of time and go from there, but I know there's an easier way. If anyone could give me a starting point it'd be great. Thanks a lot.