dcarch

I don't see the reasoning. There are so many other experiments to show 14.7 lbs/sq. in. of force without vacuum, any water or potato starch involved. As I said, if you have to climb up outside of a skyscraper, you better use suction cups, not cut potatoes. dcarch

I know this is stupid, but fun. When I order pizza, the whole pie, I keep the box and that little plastic chair after finishing the pizza. I would serve my home made pizza in one of those boxes to guests. Always gets smiles. Also the box keeps the pizza crust in the best condition. dcarch

Good experiment pbear. Frankly I am very puzzled why it is so difficult to explain atmospheric pressure and two closely attached surface. May be i am not a good ex plainer, but I thought the examples in the videos definitely explained it well. I guess not. I am also puzzled why Rotuts only picked the "swing" example in the link he gave to dispute, but totally ignored the example (copied below) in that link right above the "swing" example, which completely explained why it has nothing to do with water elasticity or potato starch when two surfaces are closely attached. dcarch "What to look for: The demonstrator will bring out a small stool and a soft-rubber baseball base from a play ground with a handle in it. He will place the base on the top of the stool, and lift up on the handle and the stool will be lifted off the floor easily. He will then show that the base is not glued to the stool by lifting the corner of the base and the stool will fall to the floor. How it happens: The stool and the base are smooth and will seal out any atmosphere from getting between them. When the demonstrator lifts on the handle, there is a small cavity formed because of the flexibility of the rubber base. There is very low pressure in this cavity, thus allowing the greater pressure of the atmosphere to push the rubber base and the top of the stool together hard enough to lift the stool from the floor. When the demonstrator lifts the corner of the rubber base, he allows air between the stool and base, equalizing the pressure with the atmosphere, and the cavity is no longer a low pressure area."

That is a very bad design. Not surprised that there will be problems. 1. The shaded pole motor actually generates a lot of heat. 2. The heating element is too close to the wiring and the motor. 3. They probably over sized a heavy gauge wire to connect to the heater to carry high current, but the heavy gauge copper also conducted too much heat to melt and eventually burn the plastic. Typically for high heat wiring, they would use fiberglass jacketed wire or Teflon jacketed wire. dcarch

"---your example just serves itself by setting up rules that have no real place in our day to day Potato Cutting World--" Perhaps. But It is perfectly acceptable in postulating. For instance, will you accept the following imaginary world? Imagine you have a bike with bearings that give you friction-less ride. and you are wearing pressurized space suit, will you accept that you can go on forever on the face of airless moon, once you get going? As a matter of fact, you can even go up hill and down hill without using force, if you apply the law of potential energy. dcarch

"" stretch without force "" I know of nothing like this. 'stretch' implies a force applied over a distance, ie work." Yes, it is absolutely possible to stretch an imaginary infinitely flexible bellow without using force. I don't remember which Newton's Law of motion/force. If you keep the rate of movement constant, there will be no force required, any resistant then can be attributed to ATM. ​Force will be require for acceleration and deceleration for a given mass, but not for a constant speed object in motion against a vertical force. dcarch

Imagine a bellow/accordion with infinitely flexible folds that you can stretch without force, now you cap both ends to make it air tight. You will experience ATM when you are trying to stretch this bellow. dcarch

Permit me to go off topic a little, although I think the thinking applies to many cooking situations. Many cooking myths happen because: In a science lesson longtime ago, this terrible example was given in the lecture to illustrate observations and conclusions, so people, please don't send me hate mail. A fellow throws a frisbee and commands his dog to fetch. The dog obliged. Then he cuts off the dog’s legs and again commands the dog to fetch a Frisbee. Obviously the dog was unable to do so. The fellow therefore concludes that dogs use legs for hearing. Apologies to all dog lovers. dcarch

"------so there is a differential pressure across that cup 'the suck' and that 'swing' in slicing a potato w a thin smooth surface ( The Knife ) I see no mechanism to create any pressure differential. one would need that differential to create the 'suck' ---" That part of the experiment can be misleading. The fact is, no force is required for the suction cup or the "swing" to be pressed together. You can find out easily by the experiment I suggested, and a few experiments in the video I linked. All you need is to come up with a way to prevent air from leaking into the space between the two surfaces, which can counteract the atmospheric pressure for you to experience the 14.7 lbs/sq in force. dcarch

Elasticity and compress-ability are not the same. Water cannot be compressed. Air gets more concentrated if compressed, following Boyle's law. As I said up thread water can provide some stickiness from surface tension, but that is no where near 14.7 lbs. dcarch

Everything you have said, and the link you provided shows the importance of 14.7 lbs of pressure on conditions when two surfaces are closely put together. A slice of potato on a shiny knife blade for example. Water is not really elastic, otherwise rain will come down in the shape of silk, not droplets. Air is not elastic, otherwise bubbles in your aquarium will look very different. dcarch

No. Relative to atmospheric pressure, which is everywhere, horizontal and vertical, up and down ( based on hydraulic theory), the force you apply to slide (not pull) an object will be horizontal perpendicular to the atmospheric pressure. Only gravitational force is always vertical, relative to objects on earth; therefore, it take no work to move horizontally ( as in riding a bicycle). The work you do is only to overcome mechanical friction and air flow resistance when riding a bike. A satellite rotates around the earth endlessly without additional energy horizontally against vertical gravitational force. Isaac Newton realized the meaning of vertical force and horizontal work when he was under the apple tree, and figured out that if a canon ball got fired at speed high enough (centrifugal force) it would surround the earth endlessly. dcarch

On the other hand, the two videos I linked, and the experiment I proposed, Which I have tried, none requires water, nor potato starch. And your newspaper example, the moment you peel one layer off, air immediately fill in to equalize the atmospheric pressure. That's how you open a can lid, if you have done food canning, and how you remove a suction cup, by peeling from the edge. dcarch

Nice experiment. Thanks. dcarch

That charred connector looks like to me connects to the heater, not to the pump. The pump looks to me is above that connection and is a very low power shaded pole motor. If that's the case, you might have run low in water at one point and the heater overheated the rubber on the connector. Or, water/moisture condensation got inside the connection and rusting started. Not much you can do. May be coat that spot with high temperature silicone and keep running the unit until it dies. I don't think it can start a fire, may be blow a fuse. dcarch

Depends on the mandoline, the first slice may stick, the second one will push the first one forward away from the blade and falls off. If you hold the mandoline sideways, if the slice is thin, friction and weak water surface tension will hold it in place. If it is thick, gravity will pull it down. If you try to pull it off the blade vertically, then the laws of force and motion will need 14 lb /sq in to overcome (assuming the potato slice is not leaking air). Second statement is very correct. Not only Air pressure pushes on all sides, same pressure also pushes from inside out. That's why an open soda can is not crushed by pressure, and you don't feel any pressure on your body. dcarch

Thank you for being polite. dcarch

Spherification with cubic shaped "spheres" is finally possible. dcarch

Not really. If you read what I have pointed out several times, and if you read Physics 101, slicing is horizontal work, it take no horizontal force to work against vertical force (atmospheric pressure). I am more than happy to keep explaining. dcarch

Kinkos and Staples have print centers. Someday, they can get themselves 3-D printers and you can go there and get a surf & turf dinner printed out for you. dcarch

Possum pizza recipe here. http://redlandrambles.com/2009/11/20/make-your-own-possum-pizza/ dcarch

I don't have that kind of knife. But I think that design can make cutting certain food better, but others worst. In any case, in the world of tools for cooking, there are plenty of products which make use of some scientific concepts to sell unscientific goods to the public. For instance, the same advertisement, "Each Glestain knife comes with a balanced, handle ". How do you have the same handle balanced for different length blades? dcarch

Another possible way is to use sintering technology. You can make porous steel knife blades to avoid the buildup of atmospheric pressure. Already, VG10, S30V, S90V steel are sintered powders for making quality knives. If only you can make porous metal sanitary. dcarch

No mysteries. It is called "vacuum" in a space that has no air. dcarch

Yes, it is possible that you need to change the way you cut potatoes, your being able to get air in between the potato and blade where there is no space for air. dcarch