A protractor is a common mathematical tool that you might need to use in physics or math. It enables you to read the angle of intersection between two lines. If you are new to math or physics, it might take a bit of practice to understand how to use it. However, you will soon find out it is an important pencil-case item.
Types of Protractor
Protractors come in a variety of designs; it might be circle with a movable arm to measure angles right through from 0 to 360 degrees. Or it might be a solid semi-circle with clear markings, but no movable arm. Architects often use a bevel protractor, which is more technical than a classroom protractor. It is consists of a straight edge with a movable, rounded arm. In a physics lesson, you are most likely to simply use a semi-circle protractor.
How to Use a Protractor
First locate the cross on the horizontal edge of the semi-circle, or at the center point of the circle. This is called the vertex. Now, place this cross on top of the angle you want to measure. The horizontal line of the vertex points to 0 degrees. Move the protractor so this line is directly on top of one of the lines of the angle to measure. Now, follow the second line which forms the angle. Read what number it points to on the edge of the protractor.
The main use of a protractor is to measure angles. A teacher will teach you how to do this in physics so you can practice trigonometry in class. Although this is mathematics, it can be used in physics to predict the height of a building, or angle of elevation of an object like a mountain or house. In a practical sense, you might be given a set of angles and distances, then told to work out your location on a map. You follow the directions to draw a triangle, and then perform a calculation to obtain the answer.
You might be given a series of questions to solve in physics that require the use of a protractor. For example, you might need to find out what happens to a ball when it bounces off a surface. You would use your protractor to measure the different angles you threw the ball at, and then determine from what angle the ball bounced off the surface. You could also investigate the effect that changes the angle of a ramp has on velocity of an object.
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