How do you measure the length  of a shadow ?
370062
Well, for one, you need the sun. After that, I'd get some sidewalk chalk, then make a marking on the ground. Then place the object whose shadow you are measuring in a position where the top of the shadow meets the marking. Then make another marking at the bottom of the shadow. Then, using a ruler, measure the distance.\n\nIf you're looking to do this mathematically, you would need to know the height of the object and the angle at which the sun is (which you can approximate based on the time of day).
964998
A shadow, by definition, is the two-dimensional projection cast by light on a three-dimensional body.  Think of it this way.  Even if you had a shadow cast by a cardboard movie cut-out of Superman, that cardboard has a given thickness that makes it three-dimensional.  However, the shadow it casts has no real thickness.
209843
If you don't want to spend money, you can use mathmatics.\n\nAll you need is a tape measure and a protractor.\n\nDepending on how tall the tree is (just guess) measure about the same distance from the tree.\n\nyou. . . . Tree  (20 ft.) \n\nNow if you can imagine that you are a vertex of a right triangle, and the tree represents the other two vertices.  Bottom of the tree is one, and the top is the other.\n\nSit down in your spot and hold the protractor level wiith the ground.  From the center of the protractor, view the top of the tree and then wrrite down the angle you are viewing through to see the top of the tree.\n\nNow using trigonomerty you should be able to closely estimate the height of the tree.\n\n\nHeight = distance (you to the tree) multiplied by the SIN(angle from protractor).\n\n\nHere is a trig table you can refer to...\nhttp://wikisource.org/wiki/Trigonometric_functions_of_angles_0%C2%B0_to_90%C2%B0_by_degree
1182820
It is different, but not for that reason. The position of your shadow is dependant not only on your position, but also on the position of the light source that you are obscuring. Think about it like this: Take a ruler and hold it in your right fingers at the end of the ruler. Grab the ruler somewhere in the middle with your left fingers. Now, while holding your right hand in place, move your left hand around and watch how the speed of the free end of the ruler (the side you're not holding) compares to the speed of your left hand. Unless you're doing something wrong, the end of the ruler will be moving faster than your hand. Now imagine that your right hand is a light source, your left hand is you, and the free end of the ruler is your shadow. It works the exact same way.
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A shadow is cast in a specific way on the spring and fall equinox (the longest and shortest day of the year).  In this way, the seasons and years can be measured.  Sort of.\n\nThis site has everything you want to know:\nhttp://en.wikipedia.org/wiki/Chichen_itza\n\nSearch for the word "equinox" in the page.  It appears a couple of times.
918551
1) darkness or a shadow\n\n2) the sides of it
353664
find the area of the cross section.... then times the area by the length... that is of course if it's a prism
228143
Absolute distance - take a ruler n measure the distance to a given object , usually , a far one .  If you happen to use mathematics and science , like measuring the luminous intensity , et al , there are some observational problems, n such a result is called an apparent measurement. That is what I have believed all these days...
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You want arc length or straight line?\n\n934.59 nm\n\naccording to the reference below.
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you can calculate the height of an object if you know a) the distance you (or some other reference point) are from it, and b) the degree of the angle from the ground where you are to the top of the object. tan(angle A) = A/B where A is the height and B is the distance. 2 of the three have to be given, i.e. you have to measure the angle with a protractor or something.
742176
write a proportion (two equal fractions) with shadow on top and height on bottom, one for the tree and one for the meter stick:\n\n5/t = 0.4/1   where t = height of tree\n\nThen cross multiply
1111107
You can count fringes when illuminating the film with a monochromatic light source. This will give you relative thicknesses across the film.  You can make an assumption that at the top where there are NO fringes and the dark part keeps stretching that the thickness is less than half the wavelength of light you are using and at the first bright fringe it is about the wavelength over 2 thick.  \n\nIf you use a sodium lamp for your light source, take care to use a low pressure sodium lamp.  High pressure lamps are nothing near monochromatic
695563
You're dealing with right triangles here. If you stand at the tip of the shadow, the length of the shadow is the adjacent side of the triangle and the height of the tree or pole is the opposite side of the triangle.  In any case, the ratio of the height to the length of the shadows will be constant.  If T = height of the tree, P = height of the pole, St = length of the shadow of the tree, and Sp = length of the shadow of the pole, then:\n\nT / St = P / Sp\nT = (P x St) / Sp\nT = (9 ft x 25 ft) / 15 ft\nHeight of the tree is 15 ft.
181462
If the angle of inclination is 30 degrees and the length of the shadow is 12 ft, from this relation we can see that tan30=height of tree/length of shadow\n\nHeight of tree = tan30*length of shadow = 6.93ft approximately.
180255
The only way that I know to do this with a normal telescope is to compare the star with others nearby of known magnitude and try to decide if it's brighter or dimmer until you find the same.\n\nOtherwise you'd need to measure the amount of light that comes from it, and I think you need computers to do that.\n\nThe magnitude scale is exponential, so deciding a magnitude ain't that simple. (ie a star of magnitude +2 is ten times brighter than a star of magnitude +3)
978520
The speed of the projected shadow upon the surface of the Earth is going to be nearly the same for every eclipse, but this effective speed does increase depending on where the shadow falls relative to the curvature of the planet.\n\nSize adds another variable, since the moon's distance from the earth varies.  In some eclipses (like an annular) the shadow of totality does not reach the surface of the earth, so the size can be as small as zero. Images in this wiki article will help you visualize this: http://en.wikipedia.org/wiki/Solar_eclipse#Geometry_of_an_eclipse\n\nSo, if I assume the moon is at its closest and the eclipse is happening with the sun/moon at an altitude of 90 degrees (noon at the equator on an equinox, for instance) I find a shadow size of a ~250km and a speed of ~1km/s.  You can approximately calculate the distortion to the shadow by multiplying by the secant of the sun's in the sky.  This actually calculates the size of the shadow on a plane tangent to the surface of the earth (rather than along the curved surface itself). Note that it is stretched only in the direction of the line passing through the observer, the moon and the sun. The speed of the shadow would scale in the same way.
304689
You can get a hollow prism, fill it with water or some liquid and find its refractive index using a spectrometer. I did that for my ISC exam.