Re: Today's jaw dropper

[Leigh Palmer <palmer@sfu.ca>]

> Here's a gem from the "How to mess with student's minds" file:
>
> Chapter 4, Problem 19 in Serway's, 4th Edition asks students to calculate
> the muzzle velocity and time of flight for a bullet which is fired
> horizontally by an astronaut standing on the Moon and which is then to
> "travel completely around the Moon and reach the astronaut at a point 10.0
> cm below its initial height."
>
> Making the assumptions that this problem seems to call for, I get
>
> time of flight = 0.35 s
> muzzle velocity = 0.10 c
>
> Who knew that the Moon was so nearly a black hole?

What was the dissipative mechanism suggested? Is this a three body
problem? If not, one would expect energy conservation to return
the bullet to its initial elevation after one orbit. Perhaps the
Moon is considered to rotate, and the bullet is in an eccentric
orbit? Please drop the other shoe. Some of us don't have copies of
Serway.

Leigh