Question

A baseball is moving in the air along the customary parabola. Ignoring air drag, where is the force on the baseball zero?

Answer 1

The force on the baseball is zero at the highest point of its trajectory, also known as the vertex of the parabola. At this point, gravity is pulling the baseball downward, but since it is moving horizontally at a constant velocity, there is no net force acting on it in either direction.