The
"Slap"
The "slap" noise
that is heard during a slapshot is a
combination of the stick hitting the ice and
then the stick hitting the puck. With a
proper slapshot the blade of the stick strikes
the ice roughly one foot in front of the
puck. When the stick strikes the ice the
force causes the stick to flex. Each
hockey stick has a flex rating on them.
This rating is in pounds force needed to flex
the stick one (1) inch. My sticks are
both rated at 100 flex. As seen in the
chart below the flex rating increases as the
stick is bowed more and more.
These sticks are made to bow and bend without
permanent deformation. The top of the
arc created by the stick bowing is centered
about the bottom hand.
This bow is important because it creates a
whipping action that helps to accelerate the
puck to a higher velocity. Since we have
the impulse of force we can now find out how
much the stick deforms.
Once again there are a few things that must be
assume:
This
calculation is once again being made based
on the player that was analyzed earlier,
Zdona Chara.
His stick has a flex rating of
100. This means that it takes 100
pounds of force to bend the stick 1
inch.
This also means that once the pound force is
converted to Newtons the new flex rating, or
k, is 440 N/in (17513 N/m)
We must also assume that the total arc is
less than 180 degrees or  .
For the purpose of simplicity I will use 75%
of the arc so the angle is 3/4.
The following will give the height of the
arc created by the stick during the wind up.
Now that we have
the height of the arc we can find the
deformation of the stick as it hits the
puck.
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