science help!!!!!!! how do contour lines measure elevation and steepness???????
919394
The other answers were correct, however I think you want to know how to convert contours into absolute steepness or a percentage of slope.  First, you must be aware that the best you are ever going to do is an approximation, as contour maps are usually approximations of the location of an elevation.  That said, to calculate slope, suppose you have a map with a 2inches/mile scale and it takes 1/2 inch to go between 400 foot contours.  1/2 inch = 1/4 mile.  Since one mile = 5280 feet, that distance is 5280/4=1320.  Now, imagine a right triangle.  The upright side is 400, it's vertex of 90 degrees is at an imaginary place in the ground at the same elevation as the lower contour directly below the second (upper) contour where you measured.  Thus the two points you measured the distance between now form two sides of an upright triangle.  The angled side (c) is 1320.  Using trigonometry (either your calculator or a table) you can calculate the length of the third side and the two unknown angles.  (boy this is hard without a graph!).  The angle where the triangle intersects the lower contour is the angle of the slope - your steepness.  Steepness is usually talked of as a "percent slope" which is two times the angle.  Why this is I don't know.\n\nI hope you got this complicated little dance.  This is actually a real-world application.  When the surveyor is going down the road, they are recording angles and slope to convert to absolute (flat) distance.  The problem is much the same.
281745
Navigation with trig uses the basic principals of the patagorean theorem (a squared + b squared = c squared), sin (pronounced sine), cosin (pronounced co-sine), and tan (tangent).  If you remember the helpful hint SOH CAH TOA (pronounced so-cah-toe-uh) it will help you to remember sin = opposite over hypotenuse, cosin = adjacent over hypotenuse, and tan = opposite over adjacent.  These refer to the sides of a traingle.  Draw a right trinagle (that is a traingle with a right angle in it).  To find any one of the angles, you use what I described above (if you know the length of the sides).  You can mix the equations up and solve for any part of it that is unknown if you know the other two.  Now, back to your question...  A navigator will usually have a chart (map) with a scale on it (measurement on the paper).  With this he / she can tell the distance between any two points, thus giving the length of the side of a traingle.  If they do this from a couple of different points, it is called "triangulation".  Now they have the "triangle", they use the stuff above to figure out the angles, distances or whatever.  Finally, they use a formula of distance = rate x time (D=RT) and variations of it (T=D/R, and R=D/T).  Let's say the navigator want to know how long it will take to get from point A to point B.  They use what I've described above to measure the distance (D), and they know how fast they are traveling (with a speedometer or airspeed indicator, etc).  Now they can use T=D/R to figure out how long it will take to get there.  In "old" times, the accuracy of charts and maps was not quite up to par, so they used the "stars" as thier maps.  these were "known" quantities, with specific angles to the horiozon (which remained fixed).  The device they used was called a "sextant".  This gave them a reading of the angle.  They would also used an hourglass for time, and a specially-made board with a rope with knots in it.  As they let out the board and it hit the water, they would "time" how many knots passed through thier fingers.  This gave them "rate" (or speed).  Using what I described above, they could figure out the rest.  Hope this helped.
433356
Topographic maps, also called contour maps, topo maps or topo quads (for quadrangles), are maps that show topography, or land contours, by means of contour lines. Contour lines are curves that connect contiguous points of the same altitude (isohypse). In other words, every point on the marked line of 100 m elevation is 100 m above mean sea level.\n\nhttp://upload.wikimedia.org/wikipedia/en/thumb/7/79/Topographic_map_example.png/300px-Topographic_map_example.png\n\nhttp://upload.wikimedia.org/wikipedia/en/thumb/4/4c/Topographic-Relief-perspective-sample.jpg/300px-Topographic-Relief-perspective-sample.jpg\n\n \nPart of the same map in a perspective shaded relief view illustrates how the contour lines of the original follow the terrainThere are several rules to note when viewing topographic maps:\n\nThe rule of Vs: sharp-pointed vees usually are in stream valleys, with the drainage channel passing through the point of the vee, with the vee pointing upstream. This is a consequence of erosion. \nThe rule of Os: closed loops are normally uphill on the inside and downhill on the outside, and the innermost loop is the highest area. If a loop instead represents a depression, some maps note this by short lines radiating from the inside of the loop, called "hachures". \nSpacing of contours: close contours indicate a steep slope; distant contours a shallow slope. Two or more contour lines merging indicates a cliff. \nOf course, to determine differences in elevation between two points, the contour interval, or distance in altitude between two adjacent contour lines, must be known, and this is given at the bottom of the map. In most cases, contour intervals are consistent throughout a map. Sometimes dashed contour lines are present; these represent half the noted contour interval.\n\nThese maps usually show not only the contours, but also any significant streams or other bodies of water, forest cover, built-up areas or individual buildings (depending on scale), and other features and points of interest.
39868
The question is:  What should I set on the sub-scale of my altimeter so that the instrument would indicate my elevation if I were on the ground at your station?\n\nANSWER:  QNH
152816
Contour curves connect points where a function of 2 variables has the same particular value. Collection of all such curves is a Contour Map.\n\nA gradient is always perpendicular to the contour curve.\n\nFor more info: \nhttp://en.wikipedia.org/wiki/Contour_line
105883
First we note that the two bases of the trapezoid are parallel and the segment joining the midpoints of the altitudes is parallel and equidistant from the bases. Therefore the vertical displacement of the midpoints of the bases from the midpoints of the altitudes is equal.\n\nIf we also contruct the segment joining the midpoints of the bases we see this intersects our other segment at its midpoint. We have now cut our quadrilateral into four triangles and it is an easy task to show that opposite triangles are congruent using SAS.
323843
If every point on the line has the same x coordinate, the line would be vertical. The formula for slope is rise/run. The "run" part would be the change in the x coordinates. Since there is no change, "run"=0. Dividing by zero is undefined, so the line's slope is undefined (not zero). Only vertical lines have an undefined slope.\n\nAlso, try plotting points. Choose any x value, and you will see that if every point has that same value, the line will be vertical regardless of the y value.\n\nAlso notice and vertical lines are not functions as they do not pass the vertical line test.
247082
Yes because to find slope you need change in y and change in x (or whatever coordinate system you use).\n\nSince you have both two x's and two y's then you're set.\n\nUse this formula: Δy/Δx where Δ stands for "change in" or (y1 - y2)/(x1 - x2)\n\nUsing the coordinates listed:\n(-2 - -2)/(6 - -8)=\n(-2 + 2)/(6 + 8)=\n(0)/(14)\n\nSince '0' divided by anything is zero, your slope is zero.\n\nThis would be a line that is parallel to the x axis 2 units below the axis.
1026484
to arrive at sea level, drive to the ocean.  then calibrate your altimeter (everyone has one.)  as you ascend, your altimeter will record the change in elevation.  you can buy one on the net for under $25.\n\nyou could also look at maps from the USGS.  they'll tell you your elevation.  globalmapper is a nifty software utility you can download for free that will help you find elevation mapping resources.\n\ni suspect GPS units will also tell you your elevation, but i'm not familiar with that.
155791
Here is a good page describing slope.\n\nhttp://mathforum.org/cgraph/cslope/slope.html
202072
Topographic maps display the elevation changes of the land.  Elevation is usually represented by isoclines, those roughly concentric lines that delineate areas of the same elevation.
962881
if acceleration is on the x axis, the slope represents 1/mass\n\nas\n\nslope = x/y = acc/force\nand\nforce=mass x acc\nso\nacc/force=1/mass\n\nif force is on the x axis, the slope represents mass\n\nas\n\nslope = x/y = force/acc\nand\nforce=mass x acc\nso\nforce/acc=mass
1027302
I don't know what ridges are, sorry.\nBut I just looked at my fingernails and I see these lines going vertically
1076306
Watershed essentially implies determining the ridge.This could be done in several ways. The classical methods are by surveying using levelling/plane tabling to prepare contour maps of the area.Contour is a line containing points of same level. once we have these maps it is easy to figure out a ridge or a valley. Modern methods are by aerial photography or satellite mapping using advance methods employing photography/infrared/radar ranging and so on.
390727
To understand what a line segment is, you have to first understand what a line is.\n\nA line is long and straight, like this:\n\n-------------------------------------------\n\nExcept that I could never actually draw real line here, just a piece of one. Why? Because real lines extend infinitely far in both directions - i.e. no matter how far you go, you'll never reach the end. So, instead, what I drew up is a line segment - a piece of a line!\n\nNow imagine that you have two line segments, and you attach one point on both of their edges together. Then, while keeping one line segments fixed (not moving) move the other line segment upwards. The resulting "thing" is an angle, and should look like: <\n\nAnother way to think about an angle is as a part of a circle. Imagine the same setup as above, only this time attach a piece of chalk to the line segment you move above (think of the line segments as sticks, or something tangle like that. The point of adding the chalk is to keep track of where the moving line goes to.) As you sweep the moving  line all the way around, the chalk will draw a circle. In fact, the way that we measure angles is based on this very idea. If you break up a circle in 360 pie shaped wedges, the angle given by each wedge is 1 degree. That's why there's 180 degrees in a straight line (half way around the circle or 360/2) and why a right triangle has a 90 degree angle (it's 1/4 of the way around the circle, or 360/4).\n\nIf you need a picture of an angle to help you imagine what I'm trying to say, here's some web sites you should check out:\n\nA picture of an angle: http://jpm-chabert.club.fr/maths/Lexique/angle_droit.gif\n\nA picture of a line segment: \nhttp://www.coe.tamu.edu/~strader/Mathematics/Geometry/PolygonLesson/Details/example1.gif\n\nA picture of how a circle is related to an angle:\nhttp://www.math2.org/math/graphs/unitcircle.gif\n\nIf you're confused about the last picture, the angle measurements that are in blue are written in a different way of measuring angles than degrees. This other way is called radians, and you'll find out more about those as you continue on in math (I first learned about them in high school.)
358834
KNOW YOUR RELATED RATES FOR CALC!! thats one thing that killed me and know your 2-D rotation around a line intergrals.
497708
to find if a line is paralel to each other, you had to find out it's gradient or slope. If the gradient is the same, then the lines are paralel.\n\nTo find gradient is rather easy.\n\nYou just plug in the points into (y2 - y1)/(x2 - x1)\n\nSo the first line is:\n(3 - - 7) / (1 - - 4)\n= (3 + 7) / (1 + 4)\n= 10/5\n= 2\n\nand the second line is:\n(10 - 6) / (4 - 2)\n= 4 / 2\n= 2\n\nyou see here that 2 = 2, so the two lines are paralel