Okay, okay, quiet down, class. Get it together, this is my time now.

Well, welcome back for another exciting lecture in the physics of sports. Hey, I saw that paper airplane, mister. See me after class.

Today we will study the physics of spiking a volleyball. Let’s begin by defining some terminology.

First, we need to have an understanding of collisions.

An example of a collision is when two billiard balls hit each other. Notice, the billiard balls change their speed and/or direction after the collision.

This is because they are exchanging momentum.

All objects have momentum. It’s a measurement of an object’s motion, described by its mass and velocity.

The mass of an object is how much matter, or stuff, the item is made of, while the velocity is the speed and direction of the moving object.

Therefore, the billiard ball example shows us that when two objects collide, their momentums will affect each other, thus creating a new momentum for each object.

Just like when NIU middle blocker Kate McCullagh spikes a ball.

McCullagh likes it when her setter, Mandi Caputo, bump sets the volleyball toward the net. This gives the ball a momentum toward the net.

McCullagh then follows the ball and jumps into the air from behind it. This provides McCullagh with a momentum that is also in the direction of the net.

“If she’s moving toward the net and the ball’s moving toward the net, she would then add her motion and it would provide some extra benefit,” said associate physics professor Laurence Lurio.

But before McCullagh can unleash her power, she must time her jump to meet the ball at a specific point in both the ball’s and her own motion.

Now this is tricky, class, so pay close attention.

Both the senior and the ball are traveling in projectile motion. This means the two are traveling in an arch, or parabolic, path.

What McCullagh is aiming to do is time her jump to reach the top of her projectile path right as the ball reaches the top of its path.

“Obviously you want to hit the ball near the top of the arch,” Lurio said. “You have to time your jump just right.”

Now, when the middle blocker times her jump right, she is finally ready for the kill.

“I try to get on top of the ball and snap my wrist,” the Woodstock native said.

Her hand is not totally flat, though. She curves her finger tips at impact.

This allows her hand to get full contact with the ball and transfer a maximum amount of momentum.

McCullagh is now releasing the full momentum she has built up from her body, arm and wrist, all of which are adding more momentum to the momentum of the ball Caputo has put in motion.

The final key is the angle of attack.

McCullagh must make sure the angle at which she hits the ball will let it travel over the net.

At the same time, though, this angle must not be too flat. If it is, it gives defenders more time to react to the attack, or even worse, sending the ball out of bounds.

Well, I see we are out of time for today. Don’t forget, our next lesson will be on how soccer players bend the ball.

Ben Gross is a football beat reporter for the Northern Star and also a physics major.