A clinometer, also known as a declinometer or inclinometer, is an instrument for measuring the slope of a slope, usually the angle between the ground or an observer and a high object. Simple, or fixed-angle clinometers require a lot of space to approach and move away when measuring an object. A protractor clinometer allows you to measure while standing still, and an easy-to-build version of the clinometer commonly used for astronomy, surveying, engineering and forestry purposes.
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Method 1 of 4: Making a Simple Clinometer
Step 1. Fold a piece of paper into a triangle
Fold the bottom right corner so it touches the left side of the paper, aligning the sides to make a triangle. If you're using a plain rectangular piece of paper, you may see "more" above this triangle. Cut or tear this part. What will remain is an equilateral triangle, with an angle of 90° and two angles of 45°.
Construction paper will make a durable clinometer, but you can use any type of paper. You may need to tie or glue the triangle to make it stronger
Step 2. Tie a straw to the longest side of the triangle
Lay a straw along the edge of the triangle, or hypotenuse, so that the end sticks out slightly from the paper. Make sure the straw is not bent or damaged, and is straight along the hypotenuse. Use insulation or glue to attach it to the paper. You will see through this straw when using the clinometer.
Step 3. Make a small hole near the end of the straw
Choose the end of the straw that is parallel to the corner, not the longer part of the paper. Use a hole punch or a sharp pen to make a hole in the triangle near this corner.
Step 4. Thread the thread through this hole
Push the thread through the hole, then tie or tape it so it doesn't slip. Use enough thread so that there are at least a few centimeters of dangling under the clinometer.
Step 5. Tie a small weight at the end of the thread
Use a metal, paperclip, or other small object. The object distance should be about 5 cm or less below the clinometer angle so that the thread can swing freely.
Method 2 of 4: Using A Simple Clinometer
Step 1. Observe a tall object through the straw
Hold the longer end of the straw near your eye and point it up from a tall object you want to observe, such as a tree. Usually you have to tilt the triangle to see the top of the target object.
Step 2. Move forward or backward until the thread is parallel to the triangle
To measure the slope of a tree, you need to find a place where you can hold the triangle flat and still see the top of the object through the straw. You can determine when the triangle goes flat, as the weight will pull the thread down parallel to one of the short sections of the triangle.
- When this happens, it means that the angle of elevation between your eye and the top of the object is 45 degrees.
- If you are crawling or standing on an object to get a better position, you will need to measure your eye level when you are in that position, rather than when you are standing normally as described in the next step.
Step 3. Use the tape measure to find the distance between this position and the base of the tall object
Like the triangle you put up, the giant triangle formed by you, the object's base, and the top of the object have two 45° angles and one 90° angle. The two shortest sides of a 45-45-90 triangle are always the same length. Measure the distance between your standing position and the base of the tall object you are measuring. The result is almost the height of the object, but there is one final step so you can get to the final answer.
If you don't have a meter, walk normally towards the object and count the steps it takes to get there. Then, if you have a ruler, measure the length of your one step and multiply it by the number of steps it takes to reach the object to get the total length (and then the height of the object)
Step 4. Add height up to the eyes to get the final answer
Since you are holding the clinometer at eye level, you are actually calculating the object's height starting at eye level above the ground. Use the tape measure to find out how high it is from the ground to your eyes, adding the result to the number you measured in the last step. Now you know the full height of the object.
Method 3 of 4: Making a Protractor Clinometer
Step 1. Get a protractor with a shape of 180°
This type of arc is shaped like a semicircle, with corners marked along the edges. You can buy them at stores that sell school supplies. Ideally a protractor with a small hole near the center of the protractor, along its straight line.
If you don't want to buy one, you can search online for a printable protractor image. Print, carefully cut along the outline, and glue the protractor paper to something sturdier, such as construction paper or an index card
Step 2. Glue a straw along the straight line
Glue a straight plastic straw near the straight part of the protractor. Make sure the straw passes two marks 0° or zero on the opposite side of the straight edge.
If you don't have a straw, roll a piece of paper into a strong cylinder and use it
Step 3. Tie a thread through the small hole in the straight edge
Many protractors have a small hole between the two 0° marks. Perpendicular from the 90° mark on the curved part. If your protractor doesn't have one, or if the holes aren't located correctly, tape or glue the threads to their proper positions. Make sure the thread hangs a few inches below the protractor.
If you are using a protractor made of paper, you can make the holes yourself using a sharp pen or punching tool. Do not try to punch holes in the plastic protractor, as it is made of fragile plastic and can break
Step 4. Tie a small weight at the end of the dangling thread
Tie a paperclip, metal, or other small weight to the end of the thread. When you hold the clinometer so that the thread falls over the curved edge, the load will pull the thread down past the angle marks on the protractor, such as 60°. This indicates what angle the clinometer is held at, which can be used to find the height of distant objects as described below.
Method 4 of 4: Using a Protractor Clinometer
Step 1. Observe the top of a tall object through a straw
Hold the clinometer so that the curved part of the protractor is facing down. Tilt the clinometer so that you can look through a straw or paper tube and see the top of a tall object you want to measure, such as a building. You can use this method to measure the angle between you and the top of the object, or the height of the object.
Step 2. Measure the angle using a protractor
Make the clinometer steady in that position, until the dangling thread stabilizes. Calculate the angle between the center of the protractor (90°), and the point where the thread passes through the edge by subtracting one by one. For example, if the thread passes through the section at an angle of 60°, the angle of elevation between you and the top of the object is 90-60=30°. If the thread passes in the 150° section, the height angle is 150-90=60°.
- The angle of elevation will always be less than 90°, because 90° is perpendicular to the sky.
- The answer will always be positive (greater than 0°). If you subtract the larger number from the smaller number and get a negative value, cross the negative symbol to get the correct answer. For example, if you calculate that 60-90=-30°, then the actual elevation angle is +30°.
Step 3. Calculate the tangent of this object
The tangent of an angle is defined as the right side of the triangle opposite the angle, divided by the part adjacent to the angle. In this case, the triangle is formed by three points: you, the base of the object, and the apex of the object. The "opposite" side of this angle is the object's height, and the adjacent side is the distance between you and the object's base.
- You can use a scientific or graphing calculator, an online tangent calculator, or a graph of a list of tangents for various angles.
- To calculate the tangent on a calculator press TAN and enter the angle you found. If the answer is below 0 or above 1, set the calculator to degrees instead of radians, and try again.
Step 4. Calculate your distance from the object
If you want to know the height of an object, you need to know the distance to the bottom of the object. Measure using a meter. If not, calculate your normal number of steps needed to reach the object, then measure the length of one step using a ruler. The total distance is the length of one step multiplied by the number of steps taken.
Some angular arcs have a ruler along their straight line
Step 5. Use your measurements to calculate the object's height
Remember, the tangent of the angle is (height of the object) / (distance between you and the object). Multiply the tangent by the distance you measure, and you'll get the object's height!
- For example, if the elevation angle is 35°, and the distance from the object is 45 units, then the object's height is 45 x tangent (35°), or 31.5 units.
- Add eye-to-eye height to your answer, because that is the distance from the clinometer to the ground.
Tips
It is easier to use an angle arc clinometer with two people working. One person looks at the object through the straw while the other records the position of the thread
Warning
- Homemade clinometers are not usually used for high-accuracy jobs, such as surveying. For the job, use an electronic clinometer.
- If the ground level you are standing on is different from the ground level of the object, you may not get accurate results. Try to measure or estimate the difference in height to subtract or add to your calculation results.
