I'm currently looking into trying to find a better way to measure straight lines when I am cutting wood for shop projects.  I had an idea the other day that it would be wonderful to have a laser that would be on a ruler.  I've tried the sound based measuring devices and they are complete junk.  Every measurement is off and repeated measures do not come close to a normal distribution... just terrible.\n\nIs the laser based measuring device much more accurate?  Where do you see this technology in the next 5 years?
123555
General Features: \nMeasuring Tool Accuracy +/- 1/4 in. at 60 ft. \nMeasuring Tool Scale Type Standard (SAE) \nMeasuring Tool Type Laser level
346937
Your data doesn't support your hypothesis or the formula.\nLook for reasons that you may have had measuring error or experimental error.
652310
Look for caliper (spelling counts).  Specifically, Vernier Caliper, and micrometer.  \n\nThose are the two major precision measuring tools.  Try the starrett.com web site.  They have a sterling reputation for quality.
409316
If you have a GPS or access to a GPS that would be the best most accurate way to measure your distance, speed and route. And they are extremely accurate.\nThen you can DL the information from the GPS to your mapping software that comes with the GPS and you can get a overall visual of your route.\nNot to mention they are coming way down in price.
519612
Different makes, and even different models from the same manufacturer, do differ.  I know this, as I have written the software for one model.  In fact, the algorithms used are a commercial secret, guarded carefully between manufacturers.  This is also the reason I am unable to provide more data, or references.\n\nYou may be able to find them for yourself, though.  Good luck.
521649
Why aren't you Americans using metric yet?\nDrag yourself into last century already!
331294
http://conversiontables.waaijweb.nl/low/index.htm\n\nhttp://www.onlineconversion.com/\n\nhttp://www.math2.org/math/general/measures.htm\n\nhttp://www.techexpo.com/techdata/conversn.html
373863
Well some I know of are:\nDumpy: Used to measure distances and it can be used to measure angles and elevations. It is actually one of the oldest there is.\nTilting: Is mainly used to measure elevations. It has a drawback because in some you see things upside down.\nAutomatic: Like the tilting is used to measure elevations but is a lot faster and more convenient.\nMy favorite though is the total station like the name says is total. It measures elevations, distances, angles and all digital. It uses a prism to which it sends a signal and measures the time it takes to travel from one place to the other to measure distance.
337262
i like having the lines in my @ss read. i think it is more accurate than a plain old palm reading! try a rump reading, you'll be suprised to see how accurate they are.
554774
Actually this is quite possible.  The key is that the laser emits a wavelength which interacts with the N2, O2, and CO2 in the air.  Each of those molecules have specific absorption and emission spectra.  As they absorb the frequencies (research their respective absorption spectra through Wikipedia or Google) of the radiation (not necessarily light) that passes through them, the light will scatter with re-emission at different frequencies (their respective emission spectra), as if reflecting off of  an object.  They wavelengths are the important part, and not necessarily the coherency (as inherent in lasers) which tends to constructively interfere to produce "laser speckle."  The primary reason one might choose a laser is ability to key the energy on the specific frequencies of interest and to control the path of the light.  You would want mirrors on the ceiling and the floor to be perfectly aligned to allow the reflected beams to cover more area of the "laser wall" with multiple reflections from partial reflectors distributing the energy from a primary source through multiple small holes in the mirrors on the floor.  Alignment of the optics, and stability (environmental isolation) would be critical issues of the system.  Normal vibrations and movements of the geology and the house will interfere with the alignment unless properly isolated from it.
614465
Every measurement has an uncertainty.  Measuring distance with a laser for example is affected by the wavelength of the laser which can be changed by air density.   Temperature affects the length of all materials.  Even outer space has distortions due to gravity of the stars and planets, gas clouds etc.
540233
I agree; c) is the right choice.  The other units are used to measure:\n\na)  power ratio\nb)  pressure\nd)  pressure (again)
619311
You'll have to give us a better idea of what you're trying to do.  An angular error of 1 second of arc corresponds to a deflection of 5 microns over a length of one metre.  It's difficult just making things smooth to 5 microns in a workshop, so any angle you measure will probably have an error in excess of 1 second anyway.\n\nI doubt any solution we can provide would fall under most definitions of "cheap".
373814
You said that your timing equipment has an accuracy of +- 33 milliseconds. In statistics, I can assume that the +- 33 milliseconds is a 95% confidence interval of the mean period of the pendulum. So, since, the critical value in a normal distribution for a 95% confidence interval is 1.96, therefore, your standard deviation is about 0.0168367 s. Working shown below,\n\n1.96 * stddev = 0.033\nstddev = 0.033/1.96 = 0.0168367\n\nSo, using the Central Limit Theorem, the standard deviation of the estimated mean is stddev/sqrt(n), where n is the number of measurements and sqrt is the square root.\n\nSo the accuracy (95% confidence interval) of the period would be\n1.96 * stddev/sqrt(n)\n= 1.96 * 0.0168367 / sqrt(n)\n= 0.033 / sqrt(n)\n\nSo as you can see the accuracy drops by a factor of 1/sqrt(n)\n\nSo, if you do 2 measurements, you get an accuracy of plus minus 0.033/sqrt(2) = 0.023 s, ie plus minus 23 milliseconds\n\nIf you do 3 measuremenets, you  get an accuracy of plus minus 0.033/sqrt(3) = 0.019 s, ie plus minus 19 milliseconds
676043
I can think of two ways to measure the absorption and reflection coefficient of a material.  The first would only work with a polished surface.  First measure the intensity of a laser beam with a photodetector, then shoot the laser beam at the surface and aim the reflection at a photodetector.  Coefficient of reflection = transmitted intensity/initial intensity  (coefficient of absorption =1-reflection).  The other, harder way, which would work with any material, is to measure the heat gain in the target.\n\nFor this you're gonna want as small a piece of the target material you can get so that the laser still completely hits it.  Now attach a thermistor to the back of the target (again the smaller and thinner the target the better, ideal would be a foil just thick enough to be completely opaque).  Now shoot the laser at the target and measure the temperature as a function of time  It should be linear up until it starts radiating nearly as fast as it absorbs energy, so take points until it starts to level off and drop points after that.  Now find the specific heat of the thermistor-target apparatus by dipping it in water with a thermometer in it, using the initial and final temperature of the water, the volume of the water, and the initial temp of the apparatus, determine the heat it absorbed per degree it's temperature changed (this will actually give you specific heat*mass which is fine).  Now convert your temperature vs. time data to heat vs. time using the specific heat you determined (temp*(specific heat*mass)).  The slope of the line of best fit for this data will give you the rate it absorbed energy in watts.  Divide this by the lasers output in watts and you get the absorption coefficient.
504286
I've never heard of the "Six Point Technique" but I HAVE heard of Six Sigma, which is a method used for quality control in many business / industrial applications.\n\nThe process was pioneered by Bill Smith of Motorola back in the 80's. The general idea was to keep an industrial process within six standard deviations (sigmas) from the median, almost eliminating defects and providing higher quality to the end user.\n\nIf this is what you were referring to, there is plenty of information available (online and off) on the subject.
505343
I think the general idea is to report as much information as possible from each measuring device. Otherwise you are just throwing away information. So for the ones that read out some digital display, you would simply report all the digits that it reads out. The other ones, where you have some choice in the matter, you would read to the nearest marking, plus estimate one more digit. \n\nAs an example, take the ruler marked with 1 mm markings:\n\ncase A. Widget length lines up exactly 10 mm \ncase B. Widget length is halfway between the 10 mm mark and the 11 mm mark. \n\nYou could actually measure a difference between A and B, so the number you report should reflect that difference. So case A would be reported as 10.0 mm, where as B would be reported as 10.5 mm. If you report both as just 10 mm (because that is how the ruler is marked) you would be missing the fact that you can measure a difference between the two. But generally, you can't estimate anymore that one place past how the ruler is marked, so you wouldn't try to report 10.55 mm, for example.