# Calculate the height of a building

1. Aug 22, 2008

### pardesi

Design a method to calculate the height of a building?this is an engineering design question....
URGENT!!! ...i need inputs !!

2. Aug 22, 2008

### mgb_phys

You have to make an attempt.
What methods can you think of?
Can you approach the building, what tools are you allowed?

3. Aug 22, 2008

### pardesi

ya i do have my method ...the method i use is we can use trigonometry(the std method) where using a sextant like instrument to measure the angle and use similarity knowing my height
any other non trivial methods or say innovatyive wud be appriciated

4. Aug 22, 2008

### mgb_phys

If this were a real engineering question the answer would just be use a total station or an RTK-GPS but presumably you are expected to come up with many different ways.
Most involve trig and similair triangles. Like measuring the length of a shadow from a stick of known height and comparing it to the length of the shadow from the building.

5. Aug 22, 2008

### pardesi

what are total stations and RTK GPS

6. Aug 22, 2008

### mgb_phys

A total station is a theodolite with a laser rangefinder, since it can measure 2 angles (the theodolite part) and distance (the laser) you can measure the relative position of anything you can see with high accuracy (mm).
RTK-GPS is a special type of GPS receiver that can measure the relative position between a pair of them to high accuracy (a few mm).
See wikipedia for details - or a survey supplies company.

As I said it depends wether this is a homework or an engineering question.

7. Aug 22, 2008

### Topher925

I like the throwing a pencil off the roof method.

8. Aug 22, 2008

### mgb_phys

Or giving the janitor a barometer!

9. Aug 25, 2008

### blimkie.k

I often use Hilit laser range finder at work similar to what MgbPhys is talking about except you just point and shoot and it tells you the distance.

If you are allwed to use on of these you could create a triangle using the side of the building and the ground. Use survey tape to measure directly out from the building a certain distance say 30 metres. Then sit back at that distance and shine the laser to the top of the building. Might want to do it when its dark so you can see the laser or use binoculars if it was a large building or if its too large it might not work at all. Use a block of wood or rock to steady the laser and get the distance. You then know 2 sides to a 90 degree triangle solve for your unknown.

Thats what I would attempt to do.