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(Introductory Activity)


Calculate a Tree's Height

 

 






Totem poles are carved from red cedar trees, which can grow as tall as 60 metres in height These trees can be found along the northwest coast of North America, from northern British Columbia to California.

What kinds of trees are there where you live? Have you ever wanted to find out what the height of a certain tree is?

You can find the height of tall objects such as trees by using a simple clinometer. A clinometer is used by highway construction engineers to measure angles of the land, by movie production engineers to measure the height of the sun, and by forestry engineers to measure the height of trees.

Clinometers show all possible angles, but for this experiment we only need to see an angle of 45 degrees.


 

 

 things to use 
You will need the following items to make your own simple clinometer:

* measuring tape
* stiff cardboard
* magic marker
* length of string
* ruler
* stone
* drinking straw
* tape
 

The picture on the right shows what your clinometer should look like after all the parts have been assembled.

If your cardboard is nine inches wide, then the slit for attaching the string, as well as the guide mark, should be nine inches from the end of the cardboard.

Tie a knot in the string and then catch it in the slit.

Draw a line from the corner of the cardboard to the point where the string is attached in order to make a 45-degree angle. Then tape the straw on along this line.

 

clinometer

 
clinometer cartoon
 
You need a partner to help you with this activity.

The stone serves as a weight to keep the string taut. Your partner can tell you when the string is exactly on the guide mark as you look through the straw at the top of the tree.

Use a measuring tape to find the distance from the tree to where you are standing and also to find the distance between your eye and the ground. Add these two distances together and to find out the approximate tree height.

You can also use your clinometer to find out the height of other tall objects, such as buildings or street lamp poles.
 
 

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