The Magnus Effect and Bernoulli's Principle : Down Ball, Roll Shot, Jump Serve
This is when a player snaps his/her wrist when making contact with the ball to create topspin on a down ball, roll shot, or jump serve. It is designed to misguide defenders by landing in a spot that does not follow a normal flight pattern. The ball seems to dip down. It also allows hitter to put more power into the hit without the ball landing out of bounds.
Forces: Magnus Force, applied force, and frictional forces cause the ball to travel with topspin. The top of the ball spins into the oncoming air and the front of the ball is moving downwards. Because the boundary layer draws the air down along with the front of the ball, more air gets pulled under the ball than goes above it. Now, since more air has to pass under the ball it gets squashed together and has to move faster. This means there needs to be a higher velocity on the lower side of the ball, and a lower velocity on the top of the ball. As the ball undergoes top-spin , it causes the velocity of the air around the top half of the ball to become less than the air velocity around the bottom half of the ball. This is because the tangential velocity of the ball in the top half acts in the opposite direction to the airflow, and the tangential velocity of the ball in the bottom half acts in the same direction as the airflow. Since the air speed around the top half of the ball is less than the air speed around the bottom half of the ball, the pressure is greater on the top of the ball. This causes a net downward force to act on the ball. This is due to Bernoulli's principle which states that when air velocity decreases, air pressure increases .
In effect, airborne flight time decreases.
Forces: Magnus Force, applied force, and frictional forces cause the ball to travel with topspin. The top of the ball spins into the oncoming air and the front of the ball is moving downwards. Because the boundary layer draws the air down along with the front of the ball, more air gets pulled under the ball than goes above it. Now, since more air has to pass under the ball it gets squashed together and has to move faster. This means there needs to be a higher velocity on the lower side of the ball, and a lower velocity on the top of the ball. As the ball undergoes top-spin , it causes the velocity of the air around the top half of the ball to become less than the air velocity around the bottom half of the ball. This is because the tangential velocity of the ball in the top half acts in the opposite direction to the airflow, and the tangential velocity of the ball in the bottom half acts in the same direction as the airflow. Since the air speed around the top half of the ball is less than the air speed around the bottom half of the ball, the pressure is greater on the top of the ball. This causes a net downward force to act on the ball. This is due to Bernoulli's principle which states that when air velocity decreases, air pressure increases .
In effect, airborne flight time decreases.