[Procyon]

From www.space.com:

81 seconds into the flight, a 20-inch, 2 1/2-pound piece of the foam fell off and struck Columbia's left wing. The shuttle Columbia was moving more than at twice the speed of sound. The impact is thought to have involved a relative speed of no more than 500 mph.

I'd have to research more to determine the airspeed 81 seconds into flight, but the relative speed was about 500 mph -- so the tests are on spot.

[kazander]

From spaceflight.com:

http://www.spaceflightnow.com/shuttle/sts107/030707impacttest/

"The foam was fired at the wing mockup at roughly 775 feet per second, or about 530 mph, at an impact angle of 22 degrees. That's higher than the impact angle during Columbia's launch. But by adjusting the impact angle, engineers were able to account for rotational energy imparted by the tumbling foam. Hubbard said the impact imparted about a ton of force to the RCC panel. All of the test parameters, taken together, represented an "average" set of conditions. The actual impact could have been somewhat worse or somewhat less violent. But the hole that was blown in RCC 8 leaves little doubt the foam strike caused the breach responsible for Columbia's destruction."

[mvpel]

http://www.aerospaceweb.org/question/aerodynamics/q0025.shtml

A graph on this page shows the shuttle's velocity at 81 seconds into the flight at around 2,000 to 2,500 feet per second, or 1,360 to 1,704 miles per hour.

[fnord]

Do you have the math to show a 500 mph relative speed?

Seems high to me, I'd expect a lot lower