Naked Science Forum

Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: dentstudent on 25/05/2009 14:49:03

Title: If you were falling at terminal velocity,
Post by: dentstudent on 25/05/2009 14:49:03

would a large curve be enough to catch you without injury? How big would the curve have to be?

Title: If you were falling at terminal velocity,
Post by: RD on 25/05/2009 17:38:12

http://www.thenakedscientists.com/forum/index.php?topic=15549.msg183081#msg183081

Title: If you were falling at terminal velocity,
Post by: dentstudent on 25/05/2009 18:04:44

The clip doesn't show it actually happening though...

Title: If you were falling at terminal velocity,
Post by: RD on 25/05/2009 18:08:17

Hopefully wingsuit man has thought better of it : if he missed the tube ... SPLAT!

Title: If you were falling at terminal velocity,
Post by: dentstudent on 25/05/2009 18:20:47

Kersplat, even.

Even so - it is still hypothetically possible, yes? But over what sort of size? And for vertical free-fall too, rather than a 3ft horizontal per 1ft vertical drop.

Title: If you were falling at terminal velocity,
Post by: Bored chemist on 26/05/2009 10:46:29

As I see it the theoretical limits are can I take the forces involved and can I dissipate the power required.

Most healthy individuals can lift a significant fraction of their weight so they can sustain themselves against an acceleration of over 1 g. Since you are only asking that they slow down at an arbitrarily slow rate then they should be able to survive a morrate acceleration.
Of course, there's a rider to that; if you are traveling at terminal velocity and only a few metres above the ground then "terminal" is the right word. There simply wouldn't be time to slow you down safely.

If I'm falling at about 120 MPH (about 50 m/s)gravity is doing work on me at 70Kg * 10 m/s/s * 50 m/s  = 35KW
That's a lot of power. In order to bring me to a halt the "brakes" would have to dissipate that power without overheating themselves or me. Could be tricky- can I land on a water slide?
I'm also carrying about 90KJ of energy; that's going to make a mess if it's dissipated in me so I'd need for it to be dumped into something else.

Having said all that obviously it's possible to do this.
All you need to do  is get the acceleration data for a free fall parachutist, work out the forces on him, and design the system to apply the same friction force as he slides to a halt as the parachute did when he  jumped.

Aiming for the top of the slide might be tricky.