Ok. What is the best way to estimate the height of a building, or tall tree that you may be standing in front of, using the minimum of equipment. Is it possible?
You need to know exactly how far away it is, and at least a crude protractor to measure the angle. That’s it.
Measure the distance between you and the building, d, then measure the angle from where your standing to the top of the buiolding, theta, (all you need to do this is a potractor, a plumb line and some sort of narrow tube, to look at the top of the building through). Then using a calculator find tan (theta) and mutiply this value by d.
Use triangles.
Yes, it is possible.
Assuming you know your height, just measure the length of the shadow you cast and the length of the shadow cast by the building. Make sure the earth doesn’t rotate appreciably between the two measurements. Then set up a proportion using similar triangles, and solve for the height of the building.
Oops, should of added tan (theta) * d = the height of the object you’re measuring (though thayt’s assuming your protarcor’s at ground level which it probably won’t be, so you’d have to add the height of you’re protractor from the ground when you measured theta to this value). Also you don’t necessarily need a tube, you could line up the top of the building just using the edge of your protractor.
Thanks amore…
Just the aswer I was looking for - all done with just the use of a tape measure!
Please proceed to the top of the Q.E.D. class!
bugger. … that’s answer! :smack:
It depends. Do you have a barometer? http://www.lhup.edu/~dsimanek/angelpin.htm
It may not be clear from this explanation, but you don’t even need a tape measure. You can measure using whatever you want - paces, shoe lengths, dollar bill lengths. Like say you’re 5’8". And your shadow is four “shoe-lengths” tall. And the building’s shadow is 23 shoe-lengths tall. Then the building’s height is 5’8" × 23 ÷ 4 = 32’7".
Assuming that you know the length of your stride, all you need is a stick the length of the inside of your arm. When you hold the stick in your fist at a right angle to the inside of your arm, you make a triangle with two 45 angles. The tangent is “one” which makes things easy. Walk until you can see the bottom of the tree is at the top of your fist and the top of the tree is at the top of the stick. The height of the tree will equal the distance to the tree. If you can accurately measure your distance to the tree, this will be an exact height. TAN45=1=opposite over adjacent. QED
Hey, it’s how they estimate timber in a lot to be cut. I’ve been paid money to do this.
From an Boy Scouts book (no kidding):
Stand some distance away, have someone of known height (esp. a round number like 6’) stand next to the object. Hold up your thumb at arms length and with another finger “measure” off a length of thumb that appears to be the same size as the person. Now step up the object, one thumblength at a time and count. Reach the top and multiply by the height of the person.
The more steps involved going up, the less accuracy, but it gives you a ballpark estimate. Going further away helps but then you should have a larger object to compare against. You don’t really need a second person, just a mark on the object a known distance from the ground.
sounds like an SAT question for which you would have about 40 seconds to work out all the numbers 