When any movement between the bodies or surfaces in the environment in which it is moving, there are always resistance force. They are also called friction forces.
They may depend on the species of the rubbing surfaces, the support body and its reaction speed, if the body is moving in a viscous medium, such as water or air.
You will need
- - dinamometr-
- - A table of coefficients treniya-
- - kalkulyator-
- - Scales.
Find the force resistance movement, whichIt acts on a moving body uniformly in a straight line. To do this, using a dynamometer or otherwise measure the force that must be applied to the body, so that it moves uniformly in a straight line. According to Newton's third law, it is numerically equal to the force of the resistance movement of the body.
Determine the power of resistance of the body movement,which moves on a horizontal surface. In this case, the frictional force is directly proportional to the floor reaction force, which is in turn equal to the force of gravity acting on the body. Therefore, the power of resistance movement in this case, or the force of friction is equal to the product of Ftr body mass m, which is measured weights in kilograms by the gravitational acceleration g? 9.8 m / s? and the proportionality coefficient?, Ftr = ?? m? g. The number? It called friction coefficient and depends on the surface coming into contact while moving. For example, to steel friction coefficient of the wood is 0.5.
Calculate the force of the resistance movement of the body,moving down an inclined plane. Furthermore a friction coefficient?, Weight m and the gravitational acceleration g, it depends on the angle to the horizontal plane?. To find a resistance force, in this case, you need to find the product of the friction coefficient, body mass, the gravitational acceleration and the cosine of the angle at which the plane is inclined to the horizon Ftr = ?? m? G? Cos (?).
When a body moves in the air at lowspeed motion resistance force Fc is directly proportional to body velocity v, Fc = ?? v. Coefficient ? It depends on the viscosity and properties of the body and the environment is calculated separately. When driving at high speeds, for example, when a body falling from a considerable height, or the vehicle is moving, the resistance force is directly proportional to the square of the speed Fc = ?? v ?. Coefficient ? calculated for further high speed.