Hi, it's my first post. When a golf ball and a bowling ball get dropped from the same height. They will both hit the same hit the ground at the same time. But when you drop a ball with radius R and another ball eith radius 2R inside a cylinder with oil then the ball with the biggest radius will fall faster. Why doesn't the balls in the oil follow the same rules as the balls in the air and fall with the same speed? Aren't both air and oil a viscous fluid?