It actually make a lot of logical sense and could have been explained easier by saying something like this: The energy is doubled with a 2 car collision but spread out over 2 cars instead of one, so the energy per car is still equal to the value of a one car collision.

So the combined energy of two identical cars at identical velocities is simply twice as much as it is for one car, or E(2) = mv^2. It doesn’t matter which direction they’re travelling, relative to each other or to a common coordinate system. The velocity of each is still v.

Kinetic energy is a linear function of mass, but a function of the SQUARE of the velocity, if you add up the velocities you would get E(3) = (1/2)(2m)(v+v)^2 or E(3) = mv^4. But the latter solution introduces a paradox; why should two bodies at a given speed and velocity always have a given total energy, unless they are aimed at each other? Why should the energy of both cars suddenly double just because they are colliding? Where does the extra energy come from?

The answer, of course, is that there is no extra energy. In each case, the energy is calculated not with reference to each body, but to a common coordinate system (in this case, the coordinate system in which the point of impact is stationary.) You add up the energies for each car, you don’t add up the velocities.

It doesn’t take an Einstein, a Newton will do.

I hope they solved it experimentally. Head-on collisions are more fun to watch.

Moral: common sense isn’t always right. The world is more complicated than you are.

Now, a related problem. A lightsail spacecraft is propelled by light photons striking the sail and imparting thrust to it. To maximize this impulse, should the sail be painted black, so that photons are absorbed, or should it be painted a highly reflective color so the photons are reflected?

I haven’t been able to watch the final season, since I am a cordcutter and Netflix lost the program last year. Hoping to pick it up at some point as I’d heard it was exceptional.

And had the same problem Jamie had- excepting the fact that closing speed between two crashing cars doesn’t really have the energy of the combined speed of the vehicles. It takes an Einstein I guess.

Happily, I’ve heard rumors of a new show featuring the “Build Team” of Kari, Grant and Tori. I saw a clip a few weeks ago of Imahara spilling the beans about the three of them hosting a “Mythbusters-like” program.

Adam Savage always seems to have things going on, especially on the internet, and I’d guess that he’ll continue to be a fixture at major conventions and gatherings for years to come. Jamie, OTOH, seems like he’ll have no regrets at all about relinquishing his celebrity (though he’ll always be a rock star in the fx biz).