You are stranded on one of the moons of a remote planet. Enough fuel
remains for but a short burst of rocket power. You calculate that you could
reach an initial velocity of 1000 meters per second while still close to
the surface. Is that enough to free you from the gravitational attraction
of the moon, or will your spaceship fall back to the surface?  You need to
find the "escape velocity" which is the smallest velocity needed to escape.

You don't know much at all about this spherical, non rotating moon; not
even the mass or the radius. You think you know the density because you
analyzed some rocks and you assume that the moon is uniform throughout. (If
you made that assumption on earth you would be way off, but on a small moon
this may not be such a bad guess). For this exercise I will stipulate that
you really know the average density and I will indicate the value at the
top of the screen. I also provide a pendulum, a metric ruler (scaled down)
to measure it's length and a stop watch (F9). Each time you run the
assignment I will give you a different moon and a different pendulum.

Your mission, should you decide to accept it, is to find the radius and the
escape velocity. To help, I will remind you that the value of the
gravitational constant is  G = 6.672 * 10^-11 (m^3 Kg^-1 s^-2) . If you
don't remember Newton's law or if you need other help read the manual. When
you are ready, press F2 and enter your answers. GOOD LUCK!
     