[bushindo]

There is a high-rise building in front of your house. You want to measure the building's height. Using common household items, list out the strategies to measure the building's height. (And no, common household items don't include laser measurement tool or a coil of rope as long as the building's height, though I guess watches with atomic accuracy are allowed).

I hope this will be more of an exercise in creativity. Members of this board have certainly surprised me with their novel and creative solutions before, and I certainly expect to see creative solutions for this one also.

[CaptainEd]

measure a small similar triangle, and scale it up.

2 yard sticks (or meter sticks, whatever you like), fastened together end to end, resulting in a 6 foot or 2 meter stick.

1 plumb bob (or string and something dense, like a pair of scissors)

1 flat mirror

1 measuring tape

1 rope long enough to reach from your front yard to the wall of the high-rise.

Assuming the high-rise does not have setbacks, so that the top of the wall nearest you is the top of the building, Using the rope, measure the distance from the high-rise to a convenient flat spot in front of your house. Call this distance W.

Place the double yardstick (meterstick) vertically at the convenient flat spot. Confirm and maintain verticality by using the plumb bob.

Place the mirror flat on the ground, closer to your house than the stick.

Adjust its position so that you can look down through the mirror, and align thetop of the meterstick to the top of the high-rise wall.

Mark on the floor next to the image of the top of the wall.

Now, measure the distance from the mark to the base of the stick. call this distance w.

Call the height of the high-rise H.

H/(W+w) = 2yds (or 2 meters)/w

wH = 2(W+w)

Calculate H:

H = 2(W+w)/w

[Guest]

We learned a way to measure the height of a building in math, similar to the way used to measure the great pyramid.

You just need a tape measure, and a helper. This works best at a time soon before or after noon, when shadows are shortest. Measure your height, and your shadow's length. Measure the length of the building's shadow, and use a proportion:

your heigth:your shadow's length=x:the buildings shadow

[Guest]

if you dont have a large measure.

I enquired of our security sources and was told I shouldn't regard it as a credible threat because the vice president wasn't regarded as credible

If you don't have a large enough measure to measure the shadow of a skyscraper you could drop something off the top. Something like a golf ball or a dart would be best, something with good aerodynamics. The height of the skyscraper will be.

H=(9.81xt²)/2

[Guest]

go to the top of the building, drop an item of known weight off the top, measure the time it takes till it hits the ground. do the appropriate math. ( this does assume some constants that in everyday life cant be assumed, but so does the shadow way as if the ground is not level and even, your measurements will be wrong)

take a ruler, measure the height of one step, climb the stairs all the way to the top while counting them. multiply step height by step count.

http://en.wikipedia.org/wiki/Tall_buildings

i have graduated cylinders in my house, but i guess you could use a ruler, some tape and glass of some sort. Fill your container with a known liquid (water will work) note the height of the water in the container while standing at the bottom. go to the top, note that the water level has raised, measure the difference, do the math

gonna go grab a bite to eat and think of more ways

[Guest]

take a piece of cardboard, make a triangle with 90,45,45 angles. hold the triangle so that it is at eye level and you are looking up the hypotenuse. walk back till you just see the top of the building in line with the hypotenuse. count the number of strides it takes to walk to the base of the building. measure your stride. multiply stride length by number of strides, add the height of your eyeball. thats the building height

use a triangle with a 90 and some other two angles. the greater the angle nearest your eye, the less you'll have to walk. follow the same procedures as before. take your stride lenght x count+height number and put it in to the equation:

tangent (angle nearest your eye) = building height / ((stride length x count)+ eye height)

[bushindo]

use a triangle with a 90 and some other two angles. the greater the angle nearest your eye, the less you'll have to walk. follow the same procedures as before. take your stride lenght x count+height number and put it in to the equation:

tangent (angle nearest your eye) = building height / ((stride length x count)+ eye height)

take a piece of cardboard, make a triangle with 90,45,45 angles. hold the triangle so that it is at eye level and you are looking up the hypotenuse. walk back till you just see the top of the building in line with the hypotenuse. count the number of strides it takes to walk to the base of the building. measure your stride. multiply stride length by number of strides, add the height of your eyeball. thats the building height

Very nice, Geoff. I'm very impressed by your creativity. Since you mentioned food, here's another way

Open your fridge and take out a nice piece of chocolate cake. Go to the building's superintendent and say "I'll give you this nice chocolate cake if you tell me this building's height".

[Guest]

One more way...

Stand still. Using eye level as a known height, mount a dry erase board flat, so that you are looking down it. Look down the straight edge of a ruler, and scribe lines for three locations: straight eye level, angle to the bottom, and angle to the top (best to use the corners to keep linearity). Simple trig off the bottom triangle gives you distance from you to the building base. Some more trig using the base distance and top angle gives you the height of the building.

[Guest]

Use your son's rocket altitrak from his boy scout days you have laying around in your garage. Walk a known distance from the building and multiply as needed.

[Guest]

s = ut + 1/2at^2

[Guest]

We all have newspaper in our houses, which are collected over months and sometimes over years.WE can glue newspaper together , till they come down from top of the building to bottom , the newspaper are of fixed size and we all have scale in our house .So if a news paper height is 100 cm and we have to use x number of newspaper sheet we can use the formula height=sizeof sheet* number of sheets.

[Guest]

We all have newspaper in our houses, which are collected over months and sometimes over years.WE can glue newspaper together , till they come down from top of the building to bottom , the newspaper are of fixed size and we all have scale in our house .So if a news paper height is 100 cm and we have to use x number of newspaper sheet we can use the formula height=sizeof sheet* number of sheets.

the same can be done with $100 bills

[Guest]

In the emergency stair, measure a step (riser). Count the number of steps. Although the number of risers may vary at some storeys, the height of each individual riser in this staircase should be consistent throughout the height of the building.

[plainglazed]

All you need is a pecil

1)Use the pencil to mark your height on the wall of the building.

2) Take a reasonable number of paces away from the building depending on it's height.

3) Turn and face the building.

4) Hold the pencil extended at arms length and put your thumb at the spot of the pencil corresponding to the base of the building when the pencil's point is at the pencil mark of your height.

5) Move the pencil up the building from thumb to tip, thumb to tip; counting as you go until you reach the top (keen hand/eye coordination required).

6) Use the pencil to multiply your height by how many lengths you counted.

[Pickett]

There is a high-rise building in front of your house. You want to measure the building's height. Using common household items, list out the strategies to measure the building's height. (And no, common household items don't include laser measurement tool or a coil of rope as long as the building's height, though I guess watches with atomic accuracy are allowed).

This question (or a similar variation of it) is often asked during technical interviews for companies...I know for a fact it was asked in some interviews to work for Google, and I've been asked this questions a few times for other companies. Basically it's just to see how creative you can be and if you can think outside the box. The one I've always liked is the one already mentioned, which is bribe the doorman of the building to tell you the height.

The other variation I've been asked is, how many ways can you measure the height of the building with nothing but a barometer?...so, assuming you have a barometer around your house, it's the same question...Thanks for posting this one...it's fun to see what people come up with

[soop]

We learned a way to measure the height of a building in math, similar to the way used to measure the great pyramid.

You just need a tape measure, and a helper. This works best at a time soon before or after noon, when shadows are shortest. Measure your height, and your shadow's length. Measure the length of the building's shadow, and use a proportion:

your heigth:your shadow's length=x:the buildings shadow

ARRGGH! I was gonna say something like this! I thought it was original though

Get a really accurate clock.

Go to the top of the building.

Make a note of the exact time in seconds that you drop the clock from the top of the building (level with the roof).

Decend and retrieve the clock.

Assuming it's broken (but the hands have not been jarred) Calculate the time it took to hit the floor, and use the fact that things accelerate at 9.80665 m/s2 in earths gravity to work out the distance it dropped.

You could find a way of measuring mass. Drop something from the roof, and use either a bathroom scale, or a viscous substance or water to determine the mass of the impact as the object strikes.

The further through the water the object moves (say a rubber ball, which floats) the more its mass will have increased.

(is it mass that increases?)

Edited May 19, 2009 by soop

[Guest]

Very nice, Geoff. I'm very impressed by your creativity. Since you mentioned food, here's another way

Open your fridge and take out a nice piece of chocolate cake. Go to the building's superintendent and say "I'll give you this nice chocolate cake if you tell me this building's height".

Yeah I was thinking that or the watch.

[bushindo]

Yeah I was thinking that or the watch.

Just thought of some more

Estimate the rate of ascent of a balloon with a few trials in your home. Let it go near the building on a windless day. The rate of ascent of the balloon should be constant if the building is not too high. Time how long it takes for the balloon to clear the building top. Multiply time by rate.

Synchronize the two watches. Let the friend stand at the bottom of the building and clap really hard at a previously specified time. Stand on the building top and record the time when you heard the clap. Multiply the time difference by the speed of sound.

[bushindo]

ARRGGH! I was gonna say something like this! I thought it was original though

You could find a way of measuring mass. Drop something from the roof, and use either a bathroom scale, or a viscous substance or water to determine the mass of the impact as the object strikes.

The further through the water the object moves (say a rubber ball, which floats) the more its mass will have increased.

(is it mass that increases?)

I think you're onto something here. if you measure the force of the impact, the you can estimate the velocity at which it travels upon impact if you know the item's mass.

It is the momentum ( momentum = velocity * mass ) that increases with speed. The mass of an object under classical physics is constant. Under relativity, every gets a bit heavier as it travels, but the mass increases for non near-light-speed are negligible.

[Guest]

Use Microsoft flight simulator to crash into the top of the virtual building. Note the altimeter reading just before the crash. Or you can get the log I think (a bit like the black box)

[Guest]

Use the second equation of motion(S = ut +0.5(gt.t)) and the clock with atomic accuracy. Drop a stone from the top of the building and use the watch to note the time taken by the stone to reach the ground. Place the values in the above equation and you have your answer.

[Guest]

i guess what can be done is ask a friend to throw a stopwatch from the top...you catch it below...

height=(g*t^2)/2

where t is the time and g is gravity

[Guest]

Dig a hole close to the building, deeper than your eye level. Look up at the building and note a point on the building that is just visible over the lip of the hole. Measure the depth of the hole and the height of the marked point on the building. Keep digging until the top of the building is just hidden by the lip of the hole. Measure the depth of the hole. Use the ratio of hole depth to visible building to calculate the height of the building. Then, take your SAT NAV out of your car, climb to the top of the building and read the altitude display, just to check.

[bushindo]

Dig a hole close to the building, deeper than your eye level. Look up at the building and note a point on the building that is just visible over the lip of the hole. Measure the depth of the hole and the height of the marked point on the building. Keep digging until the top of the building is just hidden by the lip of the hole. Measure the depth of the hole. Use the ratio of hole depth to visible building to calculate the height of the building. Then, take your SAT NAV out of your car, climb to the top of the building and read the altitude display, just to check.

I like this one. I was eating watermelon and this post nearly made me choke with laughter.

[Guest]

This reminds me of a certain urban legend I heard in college. A professor asks how a building's height can be measured using a barometer and the student comes up with a few answers that have nothing to do with air pressure.

http://www.snopes.com/college/exam/barometer.asp

[Guest]

Wow, so many ways... here is another.

Take a bucket from home and go to the top floor of the building, measure the time take to fill the bucket of water. Do the same, on the ground floor.

The drop in pressure is related to the height of the building.

Its a perfect world and we assume the pipes don't have friction. Do the math, know the height

Edited June 2, 2009 by adiace