How fast must a 10 meter rocketship be traveling for an observer on Earth to see this rocketship measuring only 0.5 meters?
Your rocketship must travel at 99.875% of the speed of light, in order for your ship to appear to shrink from 10m to 1/2m.
+118723 It depends how the measurement is taken but apparent length has more to do with the direction of travel in relation to the observer.
If it were stopped but tilted 30 degrees off the vertical it would appear half length.
If the angle was less the length would also be less. At a 20 to 1 ratio the angle would probably be 0 and you'd really be measuring the diameter of the base of the rocket.
I guess it depends on your perspective.
