Thursday, 23 June 2011

Why Spinning Ball Change Its Direction In Air?


 
The ball change its direction due to pressure difference in air(connect to ball) by the time of moving of the ball, will rotate about a particular axis of rotation.
Imagine a ball spinning about a vertical axis & moving in some velocity in horizontal direction   (in still air).
Let’s think the situation that, center of the ball is at rest and it spin in anticlockwise direction, about a vertical axis .The velocity of air is in opposite direction that of motion of the ball(as shown in the fig).

The speed of air(contact to the ball) at point A is increase by the spin of ball & the speed of air at point B is decrease by the spin of ball. So air pressure at  A is decrease as compare to pressure at B[AS TO BBERNOULLI’S EQUATION(P+ρgh+1/2ρv2=constant)].
(P= Pressure, ρ=Density, g=acceleration due to gravity, h=height, v=velocity of air)
As per pressure difference of air (less at A & more at B)the ball change its direction(towards point A).
It’s happened in everything(depend up on shape) which spinning continuously.

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