Know how pressure counts sliding friction

1. yes. When the roughness of the contact surface is the same, the sliding friction f is proportional to the positive pressure: F= μ N μ Is the dynamic friction coefficient), so μ= f/N

2. Use the spring dynamometer to weigh the gravity g, then the pressure on the horizontal table f = g, use the spring dynamometer to pull the object horizontally and uniformly in a straight line, read out the tension F of the dynamometer, then the sliding friction f = F

3. In the vertical direction, the object is subjected to the vertical downward gravity g and the vertical upward friction F. let the proportional coefficient of friction and pressure be K 1) When the pressure between the object a and the wall is F 2, the object slides down at a constant speed and is in a state of equilibrium. According to the equilibrium condition, g = f, then k = 2F, f = 2G F 2) When the pressure between the object and the wall is f 3, the sliding friction f ′ = k, F 3 = 2G F × F 3 = 2G 3 So C

4.

Calculation formula F of sliding friction= μ N Where f is the sliding friction, μ It's the coefficient of sliding friction, and N is the positive pressure between two objects. It's not hard to see that the coefficient of friction μ The larger the positive pressure is, the greater the sliding friction is

(1) in the force analysis of the object, we must first analyze the elastic force, and then analyze the sliding friction. In general, the method of orthogonal decomposition of coordinate system is adopted in force analysis

(2) if there is sliding friction, the formula F can be used= μ N. Where n is the positive pressure, not necessarily equal to the object's gravity mg

The

definition method is the most basic method to judge the direction of friction, which is true for both static friction and sliding friction

when two objects in contact with each other make relative motion or have the tendency of relative motion, a force that hinders the relative motion or the tendency of relative motion will be generated on the contact surface, which is called friction. From the definition of friction, the direction of friction is to hinder the relative movement direction or relative movement trend (direction)

In many cases, for physics problems, it will involve the identification of friction properties; In other words, the known conditions in the title can not directly determine whether the friction is sliding or static

At this time, the first step to solve the problem is to determine the nature of friction

in judging the nature of friction, first of all, it is assumed that the static friction is the whole, and the acceleration of the whole is calculated. When using the maximum static friction (sliding friction) of a single object (usually the object subject to friction only) to determine whether this acceleration can be provided

1, if it is possible, it is assumed that there is static friction between them

If the hypothesis does not hold, it must be sliding friction

5. If we know the pressure between two contact surfaces, we don't need to consider gravity. Gravity is often confusing. The direct contact surface pressure is multiplied by the friction coefficient.

6. If you pull on the horizontal plane, the sliding friction f = (mg-f1 * sin30) f
if you pull on the inclined plane, you need to carry out the force analysis, use the orthogonal method to get the resultant force of the vertical inclined plane is the positive pressure,
then use the formula of sliding friction to solve it_ I don't know how to ask

7. It depends. If the increase of pressure does not change the condition of the contact surface, and the movement does not stop, the greater the friction!

8. If it is pulled on the horizontal plane, the sliding friction f = (mg-f1 * sin30) f
if it is pulled on the inclined plane, the force analysis should be carried out, and the resultant force of the vertical inclined plane obtained by the orthogonal method is the normal pressure,
then the sliding friction formula is used to solve. Hope to help you_ ∩) O
don't know how to ask