Originally Posted by
Winemaker
Actually this is not how it works. A ballistic trajectory is the path of an un-powered projectile that is affected by gravity. The only flight path where the projectile slows to zero vertical velocity is a vertical launch. .
Velocity is a vector with components in x,y and z. ORAC clearly referred to zero vertical velocity, ie the z component. If it went up and came back down, then at some point, the vertical component was zero regardless of the shape of the trajectory.
Originally Posted by
Winemaker
Since I'm being pedantic, I'll also point out that a falling object in the atmosphere will reach some terminal velocity, determined by its drag characteristics; for a sky diver it's about 120 mph. I seriously doubt any dropped object in the atmosphere will go supersonic.
I don't see why not if the object has a small enough cross section, a large enough mass and some fins to keep the pointy end at the front. Also bear in mind that the air density is much lower during the upper part of the trajectory.
ps: since you mentioned sky divers, low level divers reach 120mph while spread but Felix Baumgartner reached 843.6 mph (Mach 1.25) on his dive