# Tip 1: How to identify the center of gravity of a plane figure

as flat figure can take a piece of heavy paper or cardboard the desired shape.The main thing that the body was thin enough.In geometry and physics in a homogeneous gravitational field under center of gravity usually understand the center of mass, or center of mass.
you need
• - a plane figure;
• - pencil;
• - line;
• - a blunt pencil;
• - needle.
Guide
1
Try to determine the center of gravity flat figure empirically.Take the new unsharpened pencil, put it vertically.On top of it, place a flat shape.Note the figure the point at which it is kept stable on a pencil.This will be the center of gravity your figure .Instead, you can use a pencil up his index finger extended.But it's difficult, because we must ensure that the finger was smooth, not swinging and shaking.
2
to demonstrate that the resulting point is the center of mass, do it in a small hole with a needle.Thread the string through the hole on one end of the tie knot - so that the thread does not pop up.Hold
ing the other end of the thread, hang the body on it.If the center of gravity defined true figure is straight, parallel to the floor.Her hips will not wobble.
3
Find the center of gravity figure geometrically.If you are given a triangle, build it the median.These segments are connected with the middle point of the triangle opposite side.The point of intersection of the medians will center of mass of the triangle.To find a middle point side, you can even be folded in half figure, but keep in mind that this would violate the uniformity figure .
4
If you have given a parallelogram, draw it diagonally.They intersect just in the center of mass.Particular cases of the parallelogram: rectangle, square, rhombus.The principle of the geometric center of the search gravity of figures similar.
5
compare the results obtained by the geometric and empirically.Draw conclusions about the course of the experiment.Minor errors are the norm.They explain non-ideal shape , imprecise devices, the human factor (minor flaws in the work, the imperfection of the human eye, etc.).

# Tip 2: How to find the center of the figure

Center figures can be found in several ways, depending on what kind of data it is already known.It is necessary to analyze to find the center of the circle, which is a set of points, which are located at an equal distance from the center, as this figure - one of the most common.
you need
• - gon;
• - line.
Guide
1
The easiest way to find the center of the circle - to bend a piece of paper on which it is drawn, making looking up to the light, that it has developed exactly in half.Then bend the sheet perpendicular to the first fold.So you get the diameters of the intersection point which is the center of the figure.
2
Of course, this method is ideal, but if a circle is drawn on paper, thin enough to be able to look at the lumen, whether complex sheet.
3
For example, the figure under consideration drew on a hard, unyielding surface, or is a separate part that is not amenable to the fold.To find the center of the circle, in this case, you need a ruler.
4
diameter is the length of the segment connecting the two points of the circle.As you know, he runs through the center, so the task of finding the center of the circle is reduced to finding the diameter and the middle.
5
Put a ruler on the circle, and then fix anywhere in the figure zero.Attach the line to a circle, having a crossing, and then move toward the center of the figure.The length of the cutting will increase until it reaches the peak point.You get the diameter, and finding the middle, and find the center of the circle.
6
circumcenter of any triangle is located at the intersection of the median perpendiculars.If a rectangular triangle, its center will always coincide with the middle of the hypotenuse.That is, the solution lies in building within the circle of a right triangle with vertices on the circle.
7
stencils for the right angle can serve as building a school or a polygon, line, or even a piece of paper / cardboard.Put in any point of the circumference of the top of the right angle, make a mark in those places where the sides angle cross the border of the circle, join them.You turned diameter - the hypotenuse.
8
same way get another diameter, the intersection of the two segments and will be the center of the circle.

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