"Don French" wrote in message
om...
You apparently never took high school physics.

Right back at ya'.

Look up Newton's first law of motion, the law of inertia.

The law of inertia has nothing to do with this.

The scramjet only had to provide
enough power to overcome the friction of air to continue at Mach 9.5
forever or until it hit something, like the earth.

In aircraft, that power is everything. Inertia provides very little support
to flight, and especially for light aircraft (like those we fly) and for
extremely fast aircraft (like the scramjet equipped test vehicle). And the
power required is the same whether you start at 0 mph or Mach 9.

To accererate the
jet from Mach 9.5 to Mach 10 takes exactly the same amount of power as
accerating from 0 mph to Mach 0.5, not very much.

You are absolutely wrong on this point. The drag at Mach 9.5 is vastly
larger than the drag at 0 mph, and as such requires vastly greater amounts
of power to accomplish any acceleration. Nearly all of the power invested
is used to overcome drag, not inertia.

And that is all that the scramjet did.

"All". Yes, you continue to demonstrate your lack of knowledge on this
point.

Yes, if you towed a Yugo behind a Porsche, and released it at 150 mph,
it would continue at 150 mph if there were no friction of air and
road.

But there IS friction. In this scenario, the friction dominates the physics
completely. Your frictionless scenario is completely irrelevant.

But it could not accelerate to 180 because the means of
propulsion depend on that same friction, unlike a jet plane, which
does not use the friction, but only has to overcome it.

Again, your frictionless scenario is completely irrelevant.

This is elementary physics, a subject that it seems fewer and fewer
people have a grasp of these days.

Yes, you are demonstrating that quite well.

Pete