Okay, so you're lame...

I'll answer them myself.

"Mark Folsom" <folsom_snip_man@redshift.com> wrote in message
news:112ilbopk6opq0e@corp.supernews.com...

Hi Guys,

Long time no post--long time no read. But, now I thought I would bless
you with another elastic collision problem, since I've been thinking
about this one...

In a vacuum, with no gravitational effects of any importance, an
initially unstressed steel cylinder 3 cm in diameter and 10 cm long with
flat ends, collides squarely endwise with an unsupported "stationary"
aluminum bar of the same diameter but 5 km long, and also with flat ends.
No adhesive or other tensile force acts at the interface. The impact
velocity is low enough so that all deformation is in the linear elastic
range.

Questions:

1. How much time passes from initial contact to separation of the two
cylinders?

About two seconds.

2. Does the steel cylinder reverse direction?

No.

3. Given V as the initial impact velocity, what is the pressure versus
time on the contact surface?

Initially, it's .71*V*sqrt(10000000*0.101/386) = 36*V (units are psi, if V
is in inches per second). After about 44 microseconds, it drops to .71
times that value; after another 44 microseconds, it drops to .71 times
*that* value, etc. After about two seconds it drops to zero.

4. What is the coefficient of restitution?

Very nearly zero.

Ciao,

Mark Folsom