The
dead spot on the racket is
where "all of the energy of
an impacting ball is given
to the racket and the racket
does not give any energy
back to the ball. [...] If a
moving racket strikes a
stationary ball at the dead
spot. then all the
rotational energy of the
racket is given to the
ball." [6]
The
node is actually a vibration
node, or the sweet spot, and
if the ball impacts this
sweet spot, the force
transmitted to the hand is
sufficiently small that the
player experiences minimal
impact
The center
of percussion (COP) is the
spot on the racket where the
axis of rotation is near the
end of the handle and the
player feels no force.
The
area of best bounce is the
area of the racket that
imparts the most energy from
the ball hitting the racket
back into the ball.
The
center of mass is the mean
position of matter in a
body.
Racket Strings
Not only does the
racket frame and the player's
swing affect the tennis ball's
trajectory but the type of string
used and way the racket is strung
affect spin and power.
The higher the
friction between a tennis ball
and the strings the more spin
can be put on the ball.
This can be
done by making strings rougher
to increase the coefficient of
friction.
Another way to
increase spin is to put less
strings in the face of the
racket.
This may seem
counter intuitive, as the more
strings in the racket face the
more friction, hence more
spin, but less strings allows
for more compression and
movement of the strings, resulting
in more energy being returned
to the ball.
"The more open the pattern,
especially the
cross strings, the more
access the ball has to the
main strings in order to
tangentially stretch them
and store and return
tangential energy,
increasing
spin-producing torque and
rebounding the ball at a
higher angle." [7]
