I have written about nachas before. But about sports.
Today, I had to take the YYM down to the Urgent Care Clinic, because he had pink eye, and we needed some antibiotic eyedrops.
On the way home, we were talking about theories of the origin of the moon, and the problem of caclulating mass, and LaGrangian points (I had not heard of these...)
The YYM is quiet for a minute, and then says, "I was wondering the other day about kinetic energy of a bullet. So I calculated the kinetic energy of a .50 caliber bullet from a M-82".
(I'm thinking, okay, not so hard, you just need estimates of the mass of the bullet, and the muzzle velocity....Still, very cool that he would actually try to calculate it!)
He goes on, "And I wondered how fast a small car, say a Smart Car, would have to be going to have the same kinetic energy."
He looks over. "About 16 miles per hour. A .50 caliber round from an M-82 sniper rifle has the same kinetic energy, at least when it leaves the barrel, as an empty Smart Car traveling at 16 miles per hour."
This, for a father, produces a flood of pure hormonal nachas. To think that this is an interesting question is pretty great. To be able to solve for it is a sign that he actually has learned something in physics. And to bring it up in casual conversation, as a random factoid, ensures his admission to the club of geek-nerds.
I'm so proud....
(UPDATE: I haven't checked the algebra. He may have gotten it wrong. But it SOUNDS about right, in order of magnitude)