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Do motion detectors or heat sensors make a dull beeping noise?

Do motion detectors or heat sensors make a dull beeping noise?

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I used to do a lot of winter backpacking, ski touring and mountaineering and the only way to keep things from freezing is to have something that produces heat and a good bit of insulation around them. There is no such thing as a 100% efficient anti-cold container. You can use insulated containers using neoprene and/or foam and reflective materials, but in severe cold they will loose any residual heat to the ambient air eventually. The only solution would be a chemical heat pack placed inside with the items you are carrying and even that would be problematic since you would have to make sure it was not close enough to materials that might OVERheat and melt. When I carry small electronics (cell phone, radio, GPS, camera) I carry them in the inside chest pockets of my insulated coat so my body heat keeps them warm. For water, don't make the mistake of trying to fill your water bottles with hot water hot water will actually freeze faster than cold water because it is already at a higher energy state. You can buy insulated bottle holders or vacuum flaks which will keep the water liquid for a while longer, but, as I said, nothing can keep it from freezing eventually if the ambient temp is cold enough. Typically in winter we would all carry a small fuel stove that we could use to warm up food and melt snow or ice for water during rest stops and in camp. That really is the only sensible option. Honestly, unless you are required to have it for maneuvers of some kind, I would NOT bring a tablet with me on a sub-zero exercise. Besides the risk of damaging it, batteries will fail quickly at low temps and you would have no way to recharge it anyway. Best to leave it in the barracks.
QUOTEI don't understand the whole space-time fabric thing? /QUOTE Simple. There is no fabric. Many people are visual creatures and you have to give them something that they can understand; just showing some math symbols won't do for them (and won't do for physicists either, actually). Describing spacetime as a fabric is something that works very well for TV shows, but no physics student uses fabrics. (Well, you know what I mean) QUOTEWhy would objects warp that invisible fabric?/QUOTE Energy density changes the space-time metric, and vice-versa. This is described the the Einstein field equations. There's no fabric involved, it's just a cute little prop that works well on TV. QUOTESpace is 3D so I don't understand the concept of a 2d plane in space and why it would only be placed at a certain angle(the angle that planets orbit)..so confused/QUOTE The well-meaning TV producers just use something they can paint on the screen. Since you can't represent 4 dimensions on TV, you only use those which are significant. They use two spatial dimensions to represent the positioning (a third dimension is irrelevant in this case, since the conservation of angular momentum keeps stuff pretty much orbiting on a plane). The vertical direction thus represents the local intensity of gravitational potential (or, in this case, the energy density, which amounts to the same thing).

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