Physicists: Where did the energy come from for Red Bull Stratos?
Buoyancy is an upward force exerted by a liquid, gas or other fluid, that opposes the weight of an immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus a column of fluid, or an object submerged in the fluid, experiences greater pressure at the bottom of the column than at the top. This difference in pressure results in a net force that tends to accelerate an object upwards.footflapsSubscriber
There’s a finite supply and we’re frittering it away apparently:Posted 5 years agobigjimSubscriber
Hmm, I’m rusty too, but from the liquid helium turning into gas, that would require a lot of thermal energy (the canisters would be cold/icy after discharging the gas), this then becomes graviational potential energy because the balloon is tethered, then when it is realised it gets turned into kinetic energy, then when the balloon can go no higher it has no more gravitational potential energy?
I’m not sure how helium is made, but presumably a compressor was used to compress it to a liquid form, so ultimately the energy source may be whatever powered that compressor, which would take us back to chemical energy if it was eg coal powered generation.
My physics teacher may be disappointed in me.Posted 5 years ago
That would be energy, no?
That was, kinda, what I was thinking over my sandwiches this lunchtime… but about as far my poor brain could go.
Part of it sort of didn’t quite make sense.
Sort of seems – if this were the case – as if Felix was possibly being powered by energy stored up ever since the planet was created 4 billion years ago.
Which is really mind-bogglingly weird.
I was hoping for a slightly more prosaic explanation! 🙂Posted 5 years agomrben100Member
So if conservation of energy………..
Helium at sea level is full of potential, balloon released and becomes utilised as kinetic as it rises transferring potential to the craft/diver. Diver jumps full of potential transferring back to kinetic as he plummets.
But on hitting the ground, now where is all the energy? Lost through heat into the atmosphere?Posted 5 years agobuzz-lightyearMember
Buoyancy from the helium. Helium is very rare in air and is collected as a by-product of mining for natural methane gas. It took energy (nuclear fusion in long-dead stars, I think) to form the helium that’s trapped in natural gas wells.
So the energy converted to the gravitational potential comes from long-dead stars.Posted 5 years agoscuzzMember
But on hitting the ground, now where is all the energy?
His parachute dissipates most of it, imparting his momentum upon the air, causing swirling eddies which dissipate into smaller and smaller eddies. Ultimately, as the momentum of each eddy lessens, the kinetic energy in the eddies gives into viscosity, generating small amounts of ‘heat’ which itself dissipates into the atmosphere.
Big whirls have little whirls that feed on their velocity,
and little whirls have lesser whirls and so on to viscosity.Posted 5 years ago
Helium at sea level is full of potential
I guess this bit probably hits at the heart of my poorly worded original question.
Given that (as far as I know) helium is formed underground by radioactive decay…
What was it that put the potential energy into the helium (that powered the balloon)?
🙂Posted 5 years agofootflapsSubscriber
The balloon is still rising and expanding(kinetic energy), it will have heated the atmosphere through friction on rising. On descent his kinetic energy is converted to heat (friction of parachute canopy / kinetic energy transferred to air) and heating in his body absorbing the small landing impact.Posted 5 years agorobinlaidlawMember
Seems like essentially, the energy came from whatever powered the process of collecting or creating the helium. Once that was done the helium stored the energy until it was used to lift capsule and ultimately fully dissipated into chaos again once the balloon went high enough to pop and release the helium again. Some of the energy will have been turned into heat by Felix himself and his parachute, and that on the capsule as they all descended again.Posted 5 years agobigjimSubscriber
But on hitting the ground, now where is all the energy? Lost through heat into the atmosphere?
Hi parachute (and his body)is losing kinetic energy to the air through friction, the air gains kinetic energy as he loses it to it. The parachute is much more efficient at doing this than his body alone. I suppose the air then loses the kinetic energy to thermal energy as the turbulent moving air slows down through its own viscosity? I guess there is some sound too.
Physicists probably rolling around laughing now.Posted 5 years agogonefishinMember
I seriously doubt that they will have used liquid helium at any point as it would need to be cooled to less than 5K (-268 C).
Big whirls have little whirls that feed on their velocity,
and little whirls have lesser whirls and so on to viscosity.
This made me smile.Posted 5 years agobuzz-lightyearMember
A prosciutto ham sandwich powered my thinking and typing.
Nuclear fission reactions provided the electricity to transmit and store my words on STW’s hard disk, and serve them back to your monitor (probably).
Pork pies and coffee powered comprehension in your brain.Posted 5 years agothisisnotaspoonMember
The altenrative to worrying about where the helium came from is to imagine it this way.
A pocket of air had to decend all that distance (loseing gravitational potential energy) and was replaced by the helium baloon and ‘basket’ so far all the energy has been transfered from graitational potential to gravitational potential but traped in a different body.
He then transfered some of this to kinetic and then to heat (via a bit of sound) as he fell.Posted 5 years ago
So.. a man climbs 24 miles above the Earth, then freefalls at Mach 1.24 on the way back down again.
From my long forgotten A-level physics, I reckon that must’ve required a fair amount of gravitational potential energy.
But, where did that energy actually come from, originally?
Helium… floating up on lighter-than-air buoyancy, but from where, how??
How is The First Law upheld in this instance??
Yours,Posted 5 years ago
So, essentially… the rest of the atmosphere will have sunk (just a little bit) to allow the helium balloon to go up (a lot).
Also note the process of inflating the balloon had already pushed the rest of the atmosphere *up* (just a little bit) to make room for it.
And the energy to do that came from the helium de-pressurising as it was released from its storage tanks into the balloon, and was originally supplied by the compressor which forced it in there in the first place 🙂Posted 5 years agoyougotcarvedMember
The answer is that the potential energy of the balloon on the ground is being swapped out for gravitational potential energy which is swapped out for kinetic energy when he drops. Thus conservation of momentum is conserved. You start with PE in the balloon, you end up with heat in the atmosphere from the parachute, all is equal!Posted 5 years ago
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