At each moment during its flight, a projectile has a velocity v and an acceleration a. The components of these variables are: vx = x component of the velocity vy = y component of the velocity ax = x component of the acceleration ay = y component of the acceleration Which of these components remain constant throughout the motion? Assume that air resistance is absent. Only vx and ay are constant. None of the variables is constant. vx, ax and ay are constant. vy, ax and ay are constant Only ax and ay are constant.