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In the kitchen version of the experiment, the marble creates a crown-shaped splash and crater as it falls into the liquid. The crater deepens to the point at which the walls start to contract. This is due to both the weight of the water outside and possibly surface tension, both of which create pressure gradients that force the collapse. Air inside this collapsing neck must escape upward or downward as the neck approaches pinch-off. It is in this escaping air that Gekle et al. found supersonic velocities—the first jet in this simple experiment (see Video 1).
The shape of the neck plays an interesting role. As the air escapes through the neck, right before the neck closes, it is accelerated to supersonic speeds as it is driven by high pressures from the collapsing cavity below to low pressures in the air above the water’s surface. Engineers have designed a similar process and shape into the convergent-divergent nozzle (or, de Laval nozzle) that is used as the exhaust port in many rocket engines. In our situation, however, the nozzle forms naturally and is quickly changing shape.
At the moment of pinch-off, very large pressures accompany the impact of the water surface on itself. In fact, the pinch-off is a type of near singularity where nearly all observables—velocities, surface curvatures, pressure gradients, etc.—become very large . Consequently, just after the pinch-off, large pressures accelerate the water upward and downward to very high velocities [3, 4]. This drives two spikes of liquid—called rebound jets—up above the water surface and another one downward into the cavity following the marble. These are our second and third jets produced by this experiment. In a low viscosity fluid such as water, the jets often quickly break up into a spray of droplets. Each of these fission events also involves a near singular pinch-off of a fluid neck . In fact, there are cases where the upward spray goes higher than the initial height of the dropped marble .
Originally posted by DropBeatsNotBombs
Remember seeing the modern day moon buggy on top gear a while back. Can't get the link to work so if you search "top gear moon buggy" in youtube it'll come up.
Still can't get my head round why the moon missions stopped. It's like everything was progressing and going straight forward when it came to humanity's space exploration.....then BANG one of the biggest pathways was block and put on hiatus.
Can read about moon mission conspiracy's all day; it was faked, it was real but made to look fake, something told space agencies to keep away, nazi's are running it etc etc. Not got a clue what to think, personally rocking the idea of it being a alien base used to watch over the earth until the right time comes.