Baseball: how do sinkers work?

[brum]

baseball: how do "sinkers" work?

in baseball, many pitchers use a pitch called a "sinker" (not a curveball, but a ball that drops once it gets near the plate)

how do they do this? I am assuming they put top spin on the ball to make it curve downward/drop, but how would they put top spin on the ball and still pitch it 80-90 mph?

 

[VBPhysics]

My intuition says that it is burnouilli's(someone correct my spelling) principle at work. in order of a base to sink down:

The air moving on the bottom of the ball has to be moving faster than the air on the top of the ball. This increase in air velocity on the bottom (acheiveable through pitching the ball with a certain orientaion and release) causes a decrease in the presure on the bottom of the ball meaning that it is being pushed down harder.

This is actually the same way airplanes work. Well airplanes go up but you get the picture.

Just a thought.

 

[krab]

Yes. Top spin is the right spin. Look up "Magnus effect". I think pitchers must throw in such a way that the ball leaves the hand between the forefinger (on top) and the thumb (on bottom), with the top fingers supplying the friction which causes top spin. But it is hard to understand how it is possible to nevertheless throw harder than 80 mph. Any major league pitchers on this forum?