If the screen width is 7 feet and the projector's throw ratio is 2.0 - 2.4:1 (because projectors have zoom lenses, they also have a range of throw ratios) then you can place your projector anywhere from 14 to 16.8 feet away from the screen.
A strain gauge (or strain gage) is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern.he gauge is far more sensitive to strain in the vertical direction than in the horizontal direction.
A narrow-gauge railway is a railway with a track gauge narrower than the standard 1,435 mm. Most narrow-gauge railways are between 600 mm and 1,067 mm. Since narrow-gauge railways are usually built with smaller radius curves, smaller structure gauges and lighter rails, they can be less-costly to build, equip and operate than standard- or broad-gauge railways. Lower-cost narrow-gauge railways are often built to serve industries and communities where the traffic potential would not justify the cos