Originally Posted by
ORAC
Assuming it was a ballistic missile and slowed to zero vertical velocity at its apex and accelerated under gravity to M2.5 - then it would have peaked at just over 50,000ft and fallen for 60 seconds before impact.
Since it’s accelerating under gravity the distance from the launch point is irrelevant, it’s the height from which the descent commenced which determines the terminal velocity.
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. Yes, the rocket will coast up to some height and then fall down vertically, but any path other than vertical will not do that.
The extreme other example is a projectile (rifle bullet for example) that is fired absolutely horizontally. During its flight the bullet will experience a downward force from gravity of 9.8 m/sec^2. If the bullet is shot from a mountain top, in one second it will fall 9.8 m. Its horizontal velocity will still be very high, reduced only by aerodynamic drag. In fact, if the bullet is fired and a weight is dropped from the same height at the same time of firing, after one second both objects (in a vacuum of course) will have dropped the same amount.
So a ballistic missile that is launched a some none vertical angle will have a component of velocity greater than zero even as it arcs over its highest altitude and down toward the target. The lower the angle of launch the greater the horizontal component of velocity. The velocity of a missile impacting a Soviet airbase will not be from the maximum altitude it reaches unless it's fired straight up (which I suspect is not the case).
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.