The acceleration of gravity on the surface of that rock is
G M / R² =
(6.67 x10⁻¹¹) (20 kg) / 100m² = 1.334 x10⁻¹¹ m/s²
That's 1.36x10⁻¹² of the acceleration of gravity on Earth's surface.
An astronaut who weighs 200 pounds on Earth would weigh
about 0.000 000 003 35 ounce on that space rock. If he were
to blink his eyes hard, he would propel himself into orbit, whereas
if he sneezed, he would escape from the rock's gravitational clutches.
