Guest

(a) Explain how a baseball pitcher can make the baseball curve to his right or left. Can we justify applying Bernoulli's equation to such a spinning baseball? (See "Bernoulli and Newton in Fluid Mechanics," by Norman F. Smith, The Physics Teacher, November 1972, p. 451.) (b) Why is it easier to throw a curve with a tennis ball than with a baseball?

(a) Explain how a baseball pitcher can make the baseball curve to his right or left. Can we justify applying Bernoulli's equation to such a spinning baseball? (See "Bernoulli and Newton in Fluid Mechanics," by Norman F. Smith, The Physics Teacher, November 1972, p. 451.) (b) Why is it easier to throw a curve with a tennis ball than with a baseball?

Grade:11

1 Answers

Aditi Chauhan
askIITians Faculty 396 Points
8 years ago
(a) A baseball which rapidly spins about an axis perpendicular to its direction of motion will curve to the right or left. The direction of the curve depends on the choice of the axis. This means it depends in what direction the baseball is rotating about its axis.While in motion, the spinning baseball experiences two lift forces. One is the Magnus force and the other the deflection force. Magnus force is more prominent. Magnus force is due to the viscous air that the spinning baseball carries around it. The flow of air around the baseball is not the same. This means that the speed of the flow of air layer is different. From Bernoulli’s equation, there is difference in the pressure on sides of the baseball.
When the baseball is spin clockwise, the Magnus force acts on the right of the direction of the motion. This due to the fact the pressure on the left side of the ball is more than on the right side.
When the baseball is spin counterclockwise, the Magnus force acts on the left of the direction of the motion. Here, the pressure on the right side of the ball is more than on the left side.
Bernoulli’s equation is applied to find out the pressure difference between the sides of the spinning baseball. So, it is justifies applying such equation to such a spinning baseball.
(b) A tennis ball has fur on its sides. This makes to have much pressure difference on its sides than the baseball. So, there would be much curve when moves through spinning on the direction of its motion. Thus, it is easier to curve the tennis ball than the baseball.

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free