When we were kids, most of us experienced the ball changing direction when we hit the ball in a curved way. We learned by experiencing the consequences of the situation without knowing how. Let's get closer to the situation from a more scientific point of view.
We need some knowledge of 'fluid mechanics' for this. Daniel Bernoulli is a well-known physicist who lived between 1700 and 1782. Bernoulli has worked on fluids and is basically the father of the following idea.In this equation, Z1 and Z2, v1 and v2, P1 and P2, ρ, and G terms represent the height, velocity, pressure, the density of the fluid, and acceleration of gravity respectively.
According to the equation, if the elevation of an object at constant pressure increases, then the velocity decreases. Or if the elevation is fixed, the pressure drops as the speed increases. Variations like this can be extracted sum will be always constant.
Now let's come to our example of 'ball'. Let's consider the picture below. Let's imagine this ball is moving from the right side to the left. The black arrows in the figure show us the direction of the wind. The ball rotates clockwise and slows down the air remaining in the bottom of the picture due to this rotation. In the same sense, the air in the upper part of the picture is also accelerating. If we assume that the change in height of the ball is too small, the increase in velocity (assuming that the ball travels at the same height) will decrease the pressure. Likewise, the decrease in speed will increase the pressure in that area.
According to physics, if there is a pressure difference between the two points, a force is created between these two points toward high pressure to low pressure. Let's think about the plane wings. The purpose of designing the wings of the aircraft is to accelerate the above air and reduce the pressure. On the other hand, it also slows down the air, increasing the pressure and creating the lift force. In the same way, sports cars spoilers and windbreakers work in the opposite way.
As we recall the example of the ball, there will be low pressure in the lower part which is the slower and lower pressure in the upper part which is faster. This difference will form a force from the lower part to the upper part. This force is called the Magnus force and the Magnus effect. In the following video, a ball dropped from an obstacle can be observed to change its motion if it is released.
