The friction force is the value with which two surfaces interact when driving. It depends on the characteristics of the bodies, the direction of movement. Due to friction, the body speed is reduced, and soon it stops.
1
The friction force is a directed value that is independent of the support of the support and the subject, since the reaction force of the support increases when driving and increasing the area. This value is involved in the calculation of the friction force. As a result, FTR \u003d N * m. Here n is the support reaction, and M is a coefficient that is a constant value if there is no need for very accurate calculations. With this formula, it is possible to calculate the force of friction of the slip, which it is necessary to consider when solving problems associated with the movement.
2
If the body rotates on the surface, then in the formula it is necessary to include rolling force. Then friction can be found according to the Formula Formula \u003d F * N / R. According to the formula, when rotating the body, its radius is important. The value F is a coefficient that can be found, knowing which material is made body and surface. This is the coefficient that is located on the table.
There are three friction strengths:
rest;
slip;
rolling.
3
The friction of peace does not allow to move the subject to the movement of which the effort is not applied. Accordingly, nails scored in a wooden surface do not fall out. The most interesting thing is that a person walks through the friction of peace, which is directed towards movement, this is an exception to the rules. Ideally, when the interaction of two absolutely smooth surfaces should not arise friction forces. In fact, it is impossible that the subject is in a state of rest or movement without resistance to surfaces.
4
During movement in the liquid, viscous resistance occurs. Unlike the air environment, the body in the liquid cannot be at rest. It starts the movement under the influence of water, respectively, there is no friction of rest in the liquid. During moving in water, the resistance to the movement occurs due to different flow rates surrounding the body. To reduce resistance when moving in liquids, the body gives a streamlined form. In nature, to overcome resistance in water on the body of fish there is a lubricant that reduces friction during movement. Remember, when moving a single body in liquids, a different resistance value occurs.
5
To reduce resistance to the movement of objects in the air, the bodies give the streamlined form. That is why airplanes are made of smooth steel with a rounded corps, a narrowed in front.
6
The friction in the liquid affects its temperature. In order for the car during frost normally traveled, it must be preheated. As a result, the viscosity of the oil decreases, which reduces the resistance and reduces the wear of parts. During moving in fluid, resistance may increase due to the occurrence of turbulent flows. In this case, the direction of movement becomes chaotic. Then the formula acquires the form: F \u003d v2 * k. Here V is the speed, and k is a coefficient depending on the properties of the body and liquid.
Knowing the physical properties of the bodies and related forces affecting the subject, you can easily be able to calculate the force of friction.
Take spring scales. Weigh the subject. Now put it on the surface and pull the dynamometer towards the movement. Take the weight of the subject. Freight residue, kg. Experience must be held in 2 directions, and find an average value. (just as you find the maximum vehicle speed). Then the formula S / TT \u003d F / M in full strength!
1
2070
Take spring scales. Weigh the subject. Now put it on the surface and pull the dynamometer towards the movement. Take the weight of the subject. Freight residue, kg. Experience must be held in 2 directions, and find an average value. (just as you find the maximum vehicle speed).
Then the formula S / TT \u003d F / M in full strength!