<font face="Arial">Captain Black Bear d wrote:</font>_________________________________________________<font face="Arial">A plane's wing has lower pressure above it because of its shape. The top part is curved, forcing the air to travel over a longer distance, which means it has to move faster creating a lower pressure.</font><div><font face="Arial">
</font></div><div><font face="Arial">
</font></div><div><font face="Arial">The baseball is different because of it's spin in relation to the wind resistance. The spin in the picture is such that the rotation opposes the air current above and favors the current below. That way it spins down. </font></div>
<font face="Arial">While you are correct
that an airplane wing's shape is made that way to make the air have to travel
further in the same amount of time (and thus faster in relation to the wing's
surface) thereby creating a lower relative pressure on the top of the wing than
on the bottom, the Bernoulli Principle still applies to a
spinningbaseball traveling through the air because, as it travels through
the air while spinning, the surface of the baseball on one side is travelling
faster in relation to the air it is travelling through than the other side.
</font><div><font face="Arial">
</font></div><div><font face="Arial">In the graphic illustration previously shown, the baseball has a spin to the left from our perspective (assuming we are looking at it from a horizontal perspective as if we were
standing off to one side of the pitcher - think standing on first base) as the ball travels through the air to
the left. This would mean the top surface (that is spinning
toward the
direction of flight) would have a higher speed relative to the air it is
travelling through than the bottom surface of the ball does because it is
travelling slower through the air and so the effective air pressure on the top surface of the ball would be relatively lower; not higher.
</font><p class="MsoNormal" style="margin-bottom: 0.0001pt; "><font face="Arial">Now, assuming that we
are still looking at the ball from the side as it would appear if we were standing
on first base as I mentioned before, and if we do not consider the effect of
gravity, the flight of the ball would tend to be altered upward, not downward
as shown. Remember that gravity is not being considered here. </font></p><p class="MsoNormal" style="margin-bottom: 0.0001pt; "><font face="Arial">
</font></p><p class="MsoNormal" style="margin-bottom: 0.0001pt; "><font face="Arial">Most
pitchers throw a ball "over the top" (not side-arm pitchers) and
because of the way the ball is gripped when thrown, usually with the fingers on
top of the ball and the thumb below it as it leaves the pitcher's hand, will
cause the ball to rotate in the opposite direction of spin as shown in the
illustration. This being the case, theball would have the tendency
to “drop” faster than it would if it had less spin or no spin whatsoever. By gripping the ball differently and thus putting
more or less spin on the ball, a pitcher can make it have different degrees
of “drop” even when the ball has the same overall velocity and time of flight
from the pitcher’s hand to the catcher’s mitt.
This is how they can “fool” the batter’s mental calculation as to where
the ball will be when it gets to his hitting zone.</font></p>
<p class="MsoNormal" style="margin-bottom: 0.0001pt; "><font face="Arial">
</font></p><p class="MsoNormal" style="margin-bottom: 0.0001pt; "><font face="Arial">I don’t know for sure but
it seems to me that the stitching on the ball would probably have a net effect of zero on
the straightness of the flight path of the ball because the stitches (if I
remember correctly) exactly mirror each other at any two points on exactly
opposite sides of the ball and thus cancel any effects on one side out by and
equal and/or opposite effect on the other side of the ball at the same time.</font></p>
<font face="Arial">lawdawg02 wrote:</font>_________________________________________________<div><span style="font-family: Tahoma, Verdana, sans-serif; background-color: rgb(255, 255, 255); ">The spin of the ball makes the pressure higher on top, which creates the downward movement you see on a 12-6 curveball. It's still Bernoulli's Principle, just applied differently for spin, as opposed to shape only.</span></div><div>
</div><div>
</div>
<div>
</div><font face="Arial">Actually the spin of the ball (as shown in the graphic illustration) would make the pressure
lower on the top, not higher, because of the increased speed of the surface of the ball in that area as opposed to the slower speed of the surface of the ball on the bottom surface.</font><div><font face="Arial">
</font></div><div><font face="Arial">It seems that you guys are trying to explain to me that the Bernoulli Principle can affect the path of the ball and on that we are in agreement. My contention is that the illustration
as drawn is incorrect and
should have shown the spin or rotation of the ball in the opposite direction for the yellow altered flight path arrow to be correct. If the red rotation arrows were reversed, the drawing would be correct. The next time you're watching tv and they show a slow motion replay of the ball being pitched, look carefully at the rotation of the ball on the way to the plate. I'll bet that you will see that the top of the ball is most likely spinning "backward" towards the pitcher unless the pitcher rotates his grip at the last instant (or unless he is a side-arm pitcher). </font></div></div>
