The physics of the hockey slap shot

Watching a hockey player score a goal can be a rush of excitement. But did you know players often take physics into account as they play? We join the Raleigh, North Carolina hockey team, The Carolina Hurricanes, and learn how torque, friction, energy transfers and vectors make for success on the rink.


Watching a hockey player score a goal can be a rush of excitement, but did you know players often take physics into account as they play?

We join the Raleigh, North Carolina, hockey team, the Carolina Hurricanes, and learn how torque, friction, energy transfers and vectors make for success on the rink.

Take a look.

Hockey is one of the fastest sports on Earth.

Players travel as fast as vehicles.

Hockey pucks scream along the ice at 90 miles per hour.

[ Cheers and applause ]

You got to know not just what you're doing, but what everyone else is doing and where everyone else is, so it's awareness, knowing where they're going, anticipating where they're going so you can get the puck to them in time or your body in time.

But it's not just practice that helps the Carolina Hurricanes win in this fast and frozen sport.

It's science.

We spent some times at a Hurricanes practice to find out.

There's a lot going on in about a split second, and these guys are so good, they figure it all out, and it happens naturally.

We've just played for so long, it just comes naturally now.

There's a lot of information being thrown at you as a goalie because you got to worry about the shooter.

You got to worry about pass options.

Is there a screen?

Could it hit somebody in front of you?

And it's a broken play.

Let's look first at the slap shot.

It's one of the most exciting moments in hockey as well as a dramatic example of how multiple types of energy are used.

The power comes from the player transferring weight from the back legs through the body, down the arms and right through to the stick.

The moving player and the moving stick are examples of kinetic energy.

That's the energy of movement, but there's more to it than that.

Obviously it's a big windup, but you're trying to hit actually the ice first.

People may not know that, and that's so you can bend the stick.

The stick is actually doing the work.

The bent stick is an example of potential energy, the energy stored in an object.

When the stick actually hits the puck, the energy stored in the bowed stick is converted to kinetic energy and released into the puck.

The overall motion of the shooter combined with the stick snapping back gives the slap shot so much power.

That torque on that stick is going to make that puck go where it wants to go or the speed at which it wants to go.

Obviously, the bigger, stronger guys can get a little more torque on their stick, a little more bent, creates a lot more velocity through the puck.

And it turns out there are different types of hockey sticks.

There's a lot of physics that goes into that, for sure.

I mean, a lot of guys use different flexes of stick.

I use more of a whippy stick, so it's easier to move, and then guys like Justin Faulk use a really stiff stick, so that means basically, if you have, you know, a lot of upper body strength and use a stiffer stick, then you're going to have a harder shot just because of the basic physics of the stick.

Here's a different type of shot.

Players call it a flick or a wrist shot.

Now you're talking about no windup, but you're still... If you watch, guys will get torque on that stick.

So we're still watching.

That stick is still going to bend.

So now the puck is right on the stick, but they're pushing into the ice to get, again, that bend on that stick to get that stick to do the work, and that whip of that stick is getting the work done.

Now, obviously they have to have strength, and you have to have timing, and you have to have skill to put the puck where you want it.

That's a whole nother game.

That's an example of what's called projectile motion, how an object propelled through the air is influenced by gravity.

As the player snaps his wrist, the puck rolls off the blade and towards the target.

The longer the puck is in contact with the stick, the faster it spins when it leaves the stick, and that spin keeps the puck on target even though gravity is pulling it down.

But you'll move it on your stick depending on where you want to shoot it, so guys will pull it in to get more torque in here, you know, get that bend.

Guys...Sometimes guys like it depending on the curve of their stick.

There's a lot of stuff going on where you release the puck off the blade.

These players are so good that, you know, they can start with the puck out here, but by the time they release it, it's 2 feet in tighter, so they're changing their angle, trying to, you know, sneak one by you.

Finally, there's passing.

It's one of the most important skills in hockey.

Passing involves speed, accuracy and a vision of what is happening.

How fast they're moving, obviously if they're moving, then for sure, you're passing it where you think they're going to be, where they're going.

That's kind of the famous Wayne Gretsky quote is he's not going where the puck is.

He's going where the puck is going.

Passing is an example of what's called velocity vectors in physics.

A vector is a quantity with more than one piece of information.

The players and the puck itself all have speed and direction.

Putting the vectors together shows where the puck needs to go to complete the pass.

Of course, hockey players do all of this instinctively.

There's a lot going into passing.

It looks like nothing is going on, but there's the pace of the pass, number one, the curve that you're passing it to.

So if the guy is on his forehand, I can fire it hard, meaning I don't have to lead him too much.

He's on his backhand where it's a harder pass to accept, I better put a little more touch on, a little more gentle, if you will, and I maybe have to put it a little ahead of him a little more so he can skate into it.

[ Cheers and applause ] There's a lot going on.

People don't need to probably know all that.

The end of the day, it's putting it in the back of the net however you can.