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Wade Flaherty out of the net
Sharks Goalie Wade Flaherty is just outside the crease after clearing the puck down the ice.

Just how fast is a goalie's reaction time?

Let's see what reaction time is required of Sharks Goalie Kelly Hrudey when an opposing player launches a speedy slapshot towards the net. If the opposing player has time to tee up and get solid wood on the puck, Hrudey could easily be facing a shot of up to 90 mph. The reaction time of the goalie can be calculated using the equation

 Time=  distance
 rate

Describing motion is a part of mechanics known as kinematics. Physicists call this a kinematic equation.



If someone shoots from the blue line, a rather generous distance of 60 feet, the time it takes for the puck to travel to the net is

 Time  d  =  60 ft
 r  90 mph


To translate 90 mph into feet per second (5280 feet =1 mile/ 3600 seconds =1 hour), then
90 x 5280 = 475, 200 feet per hour.

 475, 200  = 132 feet per second = 90 mph
 3600


 60 feet  = .456 seconds
 132 feet per second

This doesn't allow very much time for the goalie to move himself and all that equipment over to save the puck. Try testing your own reaction time, for a better understanding of what a goalie has to do.


How fast are you? (modified from the book The Sporting Life)

You can measure your reaction time with just a yardstick and some help from a friend. Rest your arm on the edge of a table or chair, with your hand hanging over the edge (this prevents you from dropping your hand down to match the yardstick's motion). Hold your thumb and index finger about an inch apart, and have a friend hold a yardstick so that its bottom end is just between your two fingers. Without warning you, have your friend drop the yardstick and, as fast as you can, close your fingers on the stick.

Note the inch reading where your fingers hold the stick. For most people, about six inches will have fallen through before they can grab the yardstick.

If you want to convert the distance the yardstick fell to a reaction time, use the following table:

Inches Fallen ReactionTime in Seconds
5.0  0.161
5.5  0.169
6.0  0.177
6.5  0.184
7.0  0.191
7.5  0.198
8.0  0.204
8.5  0.210
Reaction Time with Yardstick
This grab at 7 inches is good enough for a web developer but wouldn't cut it for a goalie.

Thinking of going pro?

The average person usually catches the yardstick around 6-8 inches; this translates to a reaction time of .177 to .204 seconds. Thinking of going pro? Wait until you consider this next situation.

If the opposing player uses the room between him and the net to his advantage and skates up so that he tees up at a distance of twenty feet from Hrudey, he will effectively minimize the time that Hrudey has to deflect the puck out of the way. If the puck is traveling at 100 mph at the time it reaches Hrudey, let's see how quick he has to be:

Time = d/t = 20 ft/90 mph = 0.152 sec.

For a reaction time like that, Hrudey would have to catch the yardstick at 4.5 inches. Maybe you'd better keep your day job.


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