If force directed parallel to a surface on which there is a body exceeds rest friction force, then the movement will begin. It will proceed until driving force exceeds the sliding friction force depending on friction coefficient. It is possible to calculate this coefficient independently.
It is required to you
- Dynamometer, scales, protractor or angle meter
Instruction
1. Find body weight in kilograms and establish it on a plain surface. Attach to it a dynamometer, and begin to move a body. Do it so that indicators of a dynamometer stabilized, supporting the constant speed of the movement. In this case the draft force measured by a dynamometer will be equal on the one hand to force of draft which is shown by a dynamometer, and on the other hand to the gravity increased by sliding friction coefficient.
2. The made measurements will allow to find this coefficient from the equation. For this purpose divide draft force into the body weight and number 9.81 (acceleration of gravity) μ=F / (m•g). The received coefficient of a sliding friction will be same for all surfaces of the same type, as well as those on which measurement was performed. For example, if the body from a tree moved on a wooden board, then this result will be fair for all wooden bodies moving sliding on a tree, taking into account quality of its processing (if surfaces rough, value of coefficient of a sliding friction to change).
3. It is possible to measure coefficient of a sliding friction and in a different way. For this purpose establish a body on the plane which can change the corner concerning the horizon. It can be an ordinary plate. Then begin to lift accurately it for one edge. When the body starts moving, rolling down in the planes as the sleigh from the hill, find a corner of its bias concerning the horizon. It is important that the body at the same time did not move with acceleration. In this case, the measured corner will be extremely small at which the body will begin to move by gravity. The coefficient of a sliding friction will be equal to a tangent of this corner μ=tg(α).
4. Generally, for finding of coefficient of a sliding friction, divide friction force into force of reaction of a support with which the body presses on a surface on which is located