Magnus Effect (Curve path by spinning ball).

Magnus effect

The Magnus effect is the commonly observed effect in which a spinning ball curves away from its principal flight path.

The Magnus effect is a lift force of tremendous importance to all athletes who want to bend the flight of a ball.

Golfers, baseball pitchers, and soccer, tennis, and table tennis players all employ this effect to curve the flight path of the ball. The game of baseball in particular is made more fascinating by the Magnus effect.

The Magnus effect operates in the following manner.

As a spinning ball moves through the air, it spins a boundary layer of air that clings to its surface as it travels along. On one side of the ball the boundary layer of air collides with air passing by. The collision causes the air to decelerate, creating a high-pressure area. On the opposing side, the boundary layer is moving in the same direction as the air passing by, so there is no collision and the air collectively moves faster. This sets up a low-pressure area. The pressure differential, high on one side and low on the other, creates a lift force (the Magnus force) that causes the ball to move in the direction of the pressure differential (i.e., from high to low).

The Magnus effect can combine with the force of gravity or fight against gravity.

The Magnus effect can be applied in any direction, and in this way an athlete can create backspin, topspin, and sidespin. Soccer players are well known for the way they use “banana kicks” (i.e., the Magnus effect) to curve free kicks and corner kicks around defenders and into the goal mouth. Tennis players and volleyball players use the Magnus effect when they apply topspin to make the ball drop suddenly while in flight.

Why windows explode, rather than implode in hurricanes?

Bernouilli's principle tells us why windows tend to explode, rather than implode in hurricanes: the very high speed of the air just outside the window causes the pressure just outside to be much less than the pressure inside, where the air is still. The difference in force pushes the windows outward, and hence explode. If you know that a hurricane is coming it is therefore better to open as many windows as possible, to equalize the pressure inside and out.

Heart attack and Bernoulli's principle.

Blood Flow and Heart Attack

Bernoulli’s principle says that the sum of potential,kinetic and pressure energy per unit mass of a incompressible,non viscous fluid remains constant.

Bernoulli's Principle states that the faster a fluid moves, the lower the pressure of the fluid.

Bernoulli’s principle helps in explaining blood flow in artery. The artery may get constricted due to the accumulation of plaque on its inner walls. This happens because of high cholesterol intake. In order to drive the blood through this constriction a greater demand is placed on the activity of the heart.

We know if the cross sectional area decreases, the velocity of the blood will increase.

The speed of the flow of the blood in this region is raised which lowers the pressure inside and the artery may collapse due to the external pressure. The heart exerts further pressure to open this artery and forces the blood through. As the blood rushes through the opening, the internal pressure once again drops due to same reasons leading to a repeat collapse. This may result in heart attack.