Somebody’s about to jump off the building

[DaveB]

I think DaveB meant the velocity after the aircraft disintegrated, not due to gravity - 120mph(ish).

I did, a quick foogle gives around 500 miles an hour as an average cruising speed for a modern airliner.

[Churchill]

I did, a quick foogle gives around 500 miles an hour as an average cruising speed for a modern airliner.

Depending on their altitude they'll still decelerate to about 120(ish)mph before hitting something big and solid.

Btw, the earth counts as very big and very solid.

[DaveB]

Depending on their altitude they'll still decelerate to about 120(ish)mph before hitting something big and solid.

Btw, the earth counts as very big and very solid.

Which is where the Terminal bit in Terminal Velocity comes from

[Churchill]

Which is where the Terminal bit in Terminal Velocity comes from

Err, no it ain't. But good one.

[doodab]

Seems unlikely to me, but I suppose there is an outside chance your limbs might shake off. Your terminal velocity would of course be lower than "hundreds of miles an hour" at lower altitudes, and at higher elevations would be greater because the atmosphere is thinner, but drag forces would also be less at height and I can't be arsed to do the calculations.

At terminal velocity, the drag force is by definition equal to the gravitational force. Gravity is slightly weaker at altitude because you are further from the earth, but at those sorts of heights it's not going to be that much weaker and the lower air density would dominate.

[Churchill]

Indeed.

Terminal velocity can be supersonic if you're high enough up.

As in falling from a balloon at 100,000ft*.




*don't try this at home.

Did that chap break the sound barrier?

[doodab]

Did that chap break the sound barrier?

Apparently not. Of course the speed of sound increases with the decreasing air density so it's quite a bit higher at altitude.

http://www.newscientist.com/article/...-freefall.html

[Gibbon]

Apparently not. Of course the speed of sound increases with the decreasing air density so it's quite a bit higher at altitude.

http://www.newscientist.com/article/...-freefall.html

Wrong. Speed of sound decreases with height due to lowering temperature, until you hit a temperature inversion higher up.

I know this as I have travelled through the sound barrier.

[suityou01]

Did that chap break the sound barrier?

that is what supersonic means.

HTH

[TimberWolf]

At terminal velocity, the drag force is by definition equal to the gravitational force. Gravity is slightly weaker at altitude because you are further from the earth, but at those sorts of heights it's not going to be that much weaker and the lower air density would dominate.

Yes, at equilibrium (terminal velocity) the drag force is the same at any height - equal and opposite to your weight. At higher altitude free-fall, prior to equilibrium, you accelerate faster. Ergo there is less of a drag force acting on you at higher altitudes, even though you accelerate and travel faster through thinner air. So limbs do not appear to be in any more danger of being shaken off at greater height as a consequence of attaining greater speed than at lower altitudes. Once at equilibrium (terminal velocity), the drag forces are the same at any height.