There's no shortage of plans online for building a simple ping pong cannon that can fire balls at hundreds of kilometres per hour. But you're probably not going to find the details of Purdue University Professor Mark French's cannon, since his creation can accelerate a ping pong ball to 1450km/h, or just over Mach 1.2.

At that speed not only do you not have the slightest chance of returning the serve, it's probably best to be nowhere near the table because as demonstrated in this video, the ping pong ball is easily capable of blasting clean through a ping pong paddle.

In fact, forget guaranteed Olympic gold were this creation ever cleared for official competition. Even though they weigh next to nothing, the ping pong balls leaving the cannon have the equivalent energy and momentum as a bullet leaving a .32 calibre pistol, meaning in the right situation they could most certainly be lethal. So maybe ping pong will finally get the respect it deserves. [YouTube via Gizmag]

Needs more slow mo.

You would have to work damn hard to make this lethal. It might have a lot of energy, but it also has very low mass and very high cross section and an easily deformed structure. It would hurt like hell, and you wouldn't want to be hit anywhere vital (eye, throat, directly over the heart, etc), but it isn't likely to cause fatal damage. To put it into perspective, while it is similar in energy to a .32, it is also similar in energy to a bean-bag round.

imagine if they intergrated this into the ping pong routines of Thai dancers...if you know what i mean
*cough* priscilla *cough*

Not really true. Damage done by a bullet is due to its kinetic energy, which is related to its velocity and mass. While the ping pong ball has very little mass, its velocity is 50% greater than a .32 bullet, thus why they have similar kinetic energy. Equal kinetic energy = just as damaging. Someone please correct me if I'm wrong.

It states it has same momentum (mass x velocity) as .32 calibre bullet. So at close range it would be just as lethal. It punched a hole right through the bat. What's not clear is how fast the velocity would drop off over range due to air resistance.

No. You are both wrong. The killing of a bullet is done by damage caused by penetration, facilitated by the energy. Penetration is related to energy divided by surface area at low velocity (around 15 joules per square centimeter for bullets) and length times the mass ratios at very high velocities. The ball will transfer its energy into the dense target of a human body without penetrating, much like a beanbag round. (Which incidentally will have a much higer momentum than a 32 ACP round). The ball does not penetrate the bat, it transfers its energy to it, knocking a piece out, it just looks like penetration. It will hurt you a lot, might break a bone, but won't kill you unless you are very unlucky. Shooters talk about one round having greater energy and therefore lethality than another, but that is valid because the other factors are negligible in their apples to apples comparisons. Finally, they can't both have the same momentum and energy with different masses and velocities. It's one or the other. For example, a 32 round has 50 percent more momentum than a ping pong ball at the same energy, and a bean bag round has almost three times the momentum of the 32 round again at the same energy, but it probably isn't going to kill you.

Edit - density ratios, not mass

Is that like saying "Don't push this button"?

I've played table tennis for years and even getting hit by a decent powered smash stings like a bitch!