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# Ketchup hourglass

Screw Newton
 (+13, -2) [vote for, against]

I have no idea what I'm talking about, but I was told ketchup is a non-newtonian fluid.

My hourglass doubles as a ketchup bottle, two clear plastic teardrop shapes joined in the middle.

 — evilpenguin, Mar 02 2009

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 Non-Newtonian basically means that you can't use it in an hourglass, because the flow is unpredictable (for today's fluid mechanics). I kind of like the idea though.

Interestingly, Custard seems to be newtonian...
 — placid_turmoil, Mar 02 2009

There are different types of custard...
 — Spacecoyote, Mar 02 2009

 The only non-newtonian object that I am familar with, is the packing left after a fig-sandwitch crackers feast.

el dueno
 — el dueno, Mar 02 2009

It would be hideously sensitive to disturbance.
 — MaxwellBuchanan, Mar 02 2009

 Non-newtonian fluids fall into several categories. [placid_turmoil] will fill your veins if you try to model these fluids using Newton's original force balance on a differential element of fluid:

 t = u* (dv/dy)

 This simple equation tells us that if a force, t, is exerted on a fluid parallel to it's surface, then the perpendicular velocity gradient, (dv/dy) will be constant. In non-newtonian fluids, this velocity gradient will not be constant, but will be dependent on a variable viscosity, u. The proportionality constant, u, is not constant at all in non-newtonian fluids. Instead, it depends on temperature, time, pressure, position in the fluid, etc. These variations can sometimes be successfully modeled, and are therefore (painstakingly) predictable, contrary to previous annotations.

 The generalized non-newtonian equation is as follows: t = u*(dv/dy) u = f(t,T,P,y,time)

 Notice how t is dependent on u and u is dependent on t. This computation feedback is essentially what drives the mathematicians mad. Finite elemental analysis can take care of most the trickery, but it takes along time to model anything significant.

 Ketchup is a shear thinning fluid, which means that it flows easier the greater the applied force (u ~ 1/t). Small forces do nothing to it. I can't reliably predict if this would work just fine, since a force balance at the bottleneck needs to account for gravity and the fact that very little shear is transmitted near the walls of a surface. I think it would be a terribly slow device, really. Also, any usage of ketchup is going to foil your timing, and flowrate is going to depend drastically with the amount left in the top, also leading to terribly confusing conversion factors and such, if any ketchup flowed through at all.

However, I'm a big fan of crazy clocks. +
 — daseva, Mar 02 2009

//Screw Newton// [marked-for-tagline]
 — FlyingToaster, Mar 03 2009

 — Spacecoyote, Mar 03 2009

cute + and I second the motion for tagline!
 — xandram, Mar 03 2009

Which one though?? The Archimedes one is kinda better.
 — daseva, Mar 03 2009

yeah 12 years later. either/or
 — xandram, Jul 17 2021

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