Water Parabola

As the thin rectangular tank spins, the water in it tends to continue moving in a straight line tangent to the circle. However, the container restrains the water and forces it to keep moving in a circle. The water near the edge goes around in one large circle at the same time that the water near the center goes around in a small circle. This means that the water near the edge travels faster than the water near the center. The faster an object moves in a circle, the larger is the force necessary to hold it in the circle.