Injuries

[donovan]

Drop a baseball off a five story building onto a thick sheet of plywood, supported by a couple of blocks, or to concrete on the ground (the heaviest bat imaginable) and see from which it bounces highest. I think the latter; the lighter bat will absorb more of the energy and transfer it to the batter.

But in this scenario, neither the plywood nor the concrete have any effective momentum. Both are stationary, so can only apply a normal force to the ball. The ball will bounce higher from the concrete, but not due to the weight or momentum of the concrete, rather due to the rigidity of the concrete affecting a more inelastic collision.

If this is right then the tradeoff becomes the weight of the bat vs. the strength of the man to swing it with sufficient force to overcome its' inertia. With some decent data this could be plotted on a graph.

In a fake math world, where all collisions are perfectly inelastic, the momentum of the bat is the only factor in determining how far the ball will go after the collision. And as billybud told us momentum = mass X speed. Therefore, increasing either the mass or the speed of the bat will have equally proportional increases in effect. Therefore, a really strong man who can swing a heavy bat just as fast as he can swing a lighter bat, will certainly perform better with the heavy bat. However, a weaker/faster man who can swing a lighter bat much faster than a heavy bat might actually have better performance with a light bat (assuming the increased speed of the swing can overcome the decreased mass of the bat). In fact, the faster, less strong man might actually hit the ball farther if his swing speed is fast enough with the lighter bat. Again, it all comes down to mass (of bat) X velocity (of bat), and optimizing that equation would appear to be something unique to each batter. In the real world, where collisions are never actually perfectly inelastic, other considerations arise such as the composition (apart from weight) of the bat. I'm not sure if this is interesting to anyone, but there it is.

I think I will concentrate on the immensity of space...something I have a modicum of chance of understanding......

Good, then let's use space as a metaphor . . .

The Motion of the Earth in travel vs the velocity of Meteor/Asteroid.
No deflection or bounce; you wind up with a crater. (broken bat?)

Now, would a comet bounce (skip), not likely --- then again, comets seem only to get caught in out gravity, spin in orbit for a few days, then fire back off into space ... or maybe that is the astronomical equivalence of Earth's outer atmosphere (exosphere) being the bat, sending the comet (baseball) in a deflective trajectory . . .

..

This is exactly what happened to Pluto and it go ejected, tossed.

[Duke1632]

Good, then let's use space as a metaphor . . .

The Motion of the Earth in travel vs the velocity of Meteor/Asteroid.
No deflection or bounce; you wind up with a crater. (broken bat?)

Now, would a comet bounce (skip) . . .

Curiously, there's evidence here in our solar system that comets/meteors can effect a skip or grazing collisions.


That's a pic of Mars, centered on the famous Valles Marineris, the largest canyon in the solar system, dwarfing Earth's Grand Canyon. The most likely explanation for the formation of Valles Marineris, one held by some astronomers, is it was created from grazing impacts of former moons/meteors. As the orbit decayed, these rocks grazed the highest parts of Mars' surface.

Here's a more compelling view:
http://upload.wikimedia.org/wikipedia/c ... p_Mars.jpg

But as your post hints, these types of collisions are highly elastic, particularly if there's an atmosphere involved. So rebounds are not so likely. Billiard balls are often used as examples of inelastic collisions, whereas silly putty will be much more elastic, and not rebound, or not as much--rather, the energy transfer is defrayed as the structure gives, even if the momentum transfer is unaffected.