PLASTIC COATING: MICROBES AID MARINE LIFE
Monday
Hundreds of millions of tons of microscopic bits of toxic plastic
waste float in the oceans and are ingested by marine life. A new
study shows some plastics seem to promote the growth of bacteria colonies that encase the material with a biofilm that seals
in toxins. Researchers are investigating how these microbes can
be effectively used to reduce poisonous plastic pollution.
April 12, 2010
Quest
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The San Diego
Union-Tribune
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science • arts • tv
‘It’s a simple game...
You throw the ball. You hit the ball. You catch the ball.’
By Scott Lafee, Staff Writer
Aaron Steckelberg and Cristina Martinez Byvik,
Pitch count
News Artists
O
r so said Joe Riggins, mythical skipper of the minor league Durham
Bulls in the 1988 movie “Bull Durham.”
But Riggins was only partly correct. Baseball may be a game of
throwing, hitting and catching a baseball, but it’s hardly simple. It is a contest
of physics, science diagrammed on a diamond by the boys of summer school.
The Padres’ home opener is today. So enough with the lollygagging!
Let the lessons, er, games begin.
Right hand pitches shown below
FASTBALL
Held by fingertips
and thrown with
normal overhand
delivery. The ball
should roll off the
fingers with back
spin, making it
“rise.” Top spin
on the ball causes
it to sink faster. The fastest
fastballs slightly exceed
100 miles mph.
Sight and sound
For the first 1.5 seconds after a hit, outfielders cannot see whether
it will be a blast or bloop. Instead, they rely on sound. A well-smacked
ball produces a sharp crack: it’s the result of air exploding outward
after the ball has briefly (less than a millisecond) wrapped itself
around the bat. A poorly hit ball generates a thud.
CURVEBALL
Squeezed
between thumb
and forefinger,
wrist cocked
to the left. On
release, the
wrist and ball
are snapped
down and to
the right, causing the ball to
spin during flight. As the
ball spins, its uneven
surface (caused by stitching)
creates air turbulence and
differing pressures on the
ball because air is passing
faster over one side than
over the other. The result —
called the Magnus effect —
is a ball that curves.
Diagonal line
to the ball
Catching a fly ball isn’t about
guessing
uessing
i where
h
it will
ill land
l d
and
d racing to that
h t spot.
t It’
It’s
about
b
perception. As
A soon
as the
th outfielder
tfi ld
d sees the
th
ball leaving the
th bat,
bat he
b
begins
moving,
i , adjusting
d
h path
his
h to
o keep
k p the
the
h b
ball o
on
a diagonal line in his
hi field
fi ld
of vision until
un glove
and
d ball
b intersect.
ersect
Outfielder
Sou
nd
SCREWBALL
Thrown like a
curveball, but
with reversed
wrist action so
that the ball
will “turn over”
and break down
and to the right.
Hitter
Plate talk express
The collision of bat and ball lasts 1/1000th
of a second, with the batter exerting 6,000
to 8,000 pounds of force. Struck squarely, a
baseball momentarily distorts to half its size.
Much of the combined energy of moving ball
and bat is lost in friction and heat caused by
the collision, but a well-hit ball can rebound
at speeds exceeding 100 mph.
The optimum ball trajectory for maximum
hitting distance is 35 degrees. Distance
increases with pitch and bat speed.
Temperature, barometric pressure and
humidity all influence a ball’s flight and
how far it travels. Every 1,000 feet
of altitude adds 7 feet of distance
to a 400-foot fly ball. Every
10 F degrees rise in
temperature, either air
or ball, adds 4 feet.
SLIDER
Thrown like a
football, with
wrist cocked
at a 90 degree
angle. The
ball behaves
somewhat like
a curveball, but
moves faster.
KNUCKLEBALL
Thrown with
fingertips dug
into the cross-seam
of ball, released
with shot putlike motion to
minimize spin.
A good knuckleball makes just a
one-quarter
revolution and moves
relatively slowly, about
65 mph. Lack of spin
and speed makes it more
susceptible to gravity and
air resistance, causing it
to move unpredictably.
Fm = S(w X v)
THE MAGNUS EFFECT
The Magnus effect refers
to surrounding turbulence
created by a moving,
spinning object, such as a
pitched baseball. It’s
calculated by measuring
angular velocity (w) and
velocity (v) of the object,
taking into account the
average air resistance
coefficient across the
surface of the object (S).
35°
Optimal
trajectory
Caught looking
No batter can watch a ball travel from pitcher’s hand
to catcher’s glove. It’s simply moving too fast. Instead,
the batter relies on anticipation and timing, beginning
his swing when the ball is 20 to 30 feet away.
A 95-mph fastball passes over the plate in less than
0.01 seconds. Swing 7 milliseconds too early, and
the ball pulls foul (for a right-handed batter). Swing
7 milliseconds too late, and it slices foul to the right.
A swing and a myth
There is no such thing as a “rising fastball,” whose upward movement would defy the laws of physics.
90 mph.
0.5 seconds
89 mph.
0.1 seconds
Batter begins swing
Actual
path
Air resistance
Pitched balls lose
velocity because
of air resistance
and gravity. A pitched
ball slows 1 mph for
every 7 feet it travels.
Gravity
A “rising fastball” is an optical illusion created by the batter’s
inaccurate anticipation of the ball’s speed and path. That’s
understandable: A 90-mph fastball travels 132 feet per
second. The batter has about 0.5 seconds to see the ball,
guess its speed and trajectory and decide whether to swing.
When the ball is moving faster than the
Perceived
batter estimates, its trajectory will be flatter
path
and it will arrive at the plate higher than
anticipated, appearing to the batter to have risen.
Pitcher
Distance (in feet)
10
20
30
40
50
Hitter
60 feet
SOURCES: Terry Bahill, University of Arizona; exploratorium.edu; NASA; Natural History; New York Times; “The Physics of Baseball” by Robert Adair; Scientific American; Mike Stadler, University of Missouri; Sports Biomechanics Laboratory, UC Davis
Catcher