5 ms·
What happens when Hyperloop breaks the sound barrier inside a tunnel? Will it always be slower than the speed of sound? If yes, why don’t we invest in MagLev tr
by lcnmrn 10y ago
What happens when Hyperloop breaks the sound barrier inside a tunnel? Will it always be slower than the speed of sound? If yes, why don’t we invest in MagLev trains instead?
- Retric 10y agoThe low pressure means not much happens. Further low pressure makes a dramatic difference in energy needs.
- nicktelford 10y agoThe maximum designed speed is less than the speed of sound inside the tube, so I don't believe this will be a problem.
- hatsunearu 10y agoHuh, I thought that speed of sound increases when pressure decreases, but it seems to be the opposite.
- GeneralMayhem 10y agoYep. Intuitively, sound propagates when particles bump into each other and transfer energy. Lower pressure means lower density, so there are fewer particles, which means it takes longer before an energized particle happens to bump into another one and propagate the wave.
- grogers 10y agoThe speed of sound is invariant to changes in pressure, it is temperature that matters.
- JoeAltmaier 10y agoHere's a graph I found. It appears highly non-linear. https://sooeet.com/speed/speed-of-sound-in-atmosphere-graph.php https://sooeet.com/speed/speed-of-sound-in-atmosphere-graph....
- hatsunearu 10y agoProbably because that isn't just v vs. pressure, it probably takes the temperature into account as well.