The geometrical point in which all gravity operating on a body at its any turn is crossed is considered the center of gravity of any body. Sometimes it does not coincide with one of body points.
It is required to you
- - body
- - thread
- - ruler
- - pencil
Instruction
1. If the body which center of gravity is required to be defined uniform and has the simple form – rectangular, round, spherical, cylindrical, square, and it has a center of symmetry, in a similar case the center of gravity coincides with the center of symmetry.
2. For a uniform core the center of gravity is located in its middle, that is in its geometrical center. Just the same result turns out also for a uniform round disk. Its center of gravity lies in a point of intersection of diameters of a circle. Therefore also the center of gravity of a hoop will appear in its center, out of points of the hoop. Find the center of gravity of a uniform sphere – it is located in the geometrical center of the sphere. The center of gravity of a uniform rectangular parallelepiped will appear on crossing of its diagonals.
3. If the body has any form if it is non-uniform, say, has dredging, is difficult to calculate a center of gravity position. Sort out where at such body the point of intersection of all gravity which affects this figure at its turning is located. It is the simplest to find this point by practical consideration, having used way of free suspension of a body on thread.
4. Consistently attach a body to thread for different points. At balance the center of gravity of a body has to lie on the line coinciding with the line of thread, otherwise gravity would set a body in motion.
5. By means of a ruler and a pencil draw the vertical straight lines coinciding with the direction of threads which were fixed in different points. Depending on complexity of a shape of a body it is required to draw two-three lines. All of them have to be crossed in one point. This point will also be the center of gravity of this body because the center of gravity has to be at the same time on all similar straight lines.
6. Define by a way of suspension the center of gravity of both a flat figure, and more difficult body which shape can change. For example, two bars connected by the hinge in the spread-out state have the center of gravity in the geometrical center, and in bent – their center of gravity appears out of these bars.