# Measuring the height of a building

1. Oct 16, 2005

### quicknote

I'm suppossed to measure the height of a building tomorrow but I'm not exactly sure of how to do it accurately.

Would using 'similar triangles' work?
I would measure the length of the tower's shadow and my shadow. Using my height and shadow length, I could calculate the angle and use that angle for the tower/shadow triangle and then caclulate the height.

I've also thought about droping an object from the top of the building and find the time it takes to reach the ground and using an equation to find the height.

There seems to be a lot of websites on the barometer joke...but nothing that really helps me out.
Is there an easier method...other than actually measuring the building?

2. Oct 16, 2005

### TOKAMAK

What's wrong with using a barometer? Are you not allowed? Your second idea sounds pretty good, where you drop an object and listen for it to hit the ground, seems like it would be quicker than trying to measure shadows and figure out angles.

3. Oct 16, 2005

### quicknote

Do the barometer suggestions even work?
Anyways I don't know where to get a barometer

I would like to do drop an object, but I just realize that I don't think we have access to the rooftop and I dont' think the windows open...so looks like I'll be using triangles :grumpy:

4. Oct 16, 2005

### Tide

Use similar triangles! You won't even need trigonometry if you situate yourself such that the tip of your shadow coincides with the tip of the building's shadow. You simply need to measure the length of your shadow, that of the building and, of course, your own height.

Regarding the barometer, pressure measurements likely won't be accurate enough but, with a good stopwatch, you can measure how long it takes for the barometer to fall to the ground from the top of the building! :)

5. Oct 16, 2005

### Tide

P.S. You'll need a Plan B - in case it's overcast!

6. Oct 16, 2005

### quicknote

Use similar triangles! You won't even need trigonometry if you situate yourself such that the tip of your shadow coincides with the tip of the building's shadow. You simply need to measure the length of your shadow, that of the building and, of course, your own height.[/QUOTE]

Thanks Tide! That not only makes more sense but so much more easier :)
I think my plan b would be to wait for the sun to come out