What are the influencing factors of sliding friction

1) The amount of pressure on the object. The greater the pressure on the contact surface, the greater the sliding friction. (2) The roughness of the surface in contact with the object (roughness of the contact surface).

The rougher the contact surface, the greater the sliding friction when the pressure on the object is the same. (3) The magnitude of sliding friction is independent of the area of the contact surface.

Sliding friction.

The influencing factors are:

1. The pressure on the object, when the roughness of the contact surface is the same, the greater the pressure, the greater the sliding friction.

2. The roughness of the surface in contact with the object (roughness of the contact surface), when the pressure on the object is the same, the rougher the contact surface, the greater the sliding friction.

(3) The magnitude of sliding friction is independent of the area of the contact surface.

4. The magnitude of sliding friction has nothing to do with the speed of the object.

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1. The magnitude of sliding friction is related to the pressure of the contact surface and the roughness of the contact surface.

2. The greater the pressure on the contact surface, the rougher the contact surface, and the greater the sliding friction.

3. Sliding friction has nothing to do with the speed of movement of the object, and has nothing to do with the size of the contact area.

Question 1: What are the factors affecting the magnitude of sliding friction (1)1 and 2; The roughness of the contact surface is the same, the greater the pressure, the greater the sliding friction; 1 and 3; When the pressure is constant, the rougher the contact surface, the greater the sliding friction.

The main steps of the experiment: put the same rectangular wooden block on the same horizontal plank, use the spring dynamometer to pull it at different speeds to do a uniform linear motion, and read the indication of each spring dynamometer.

The conclusion is that if the three times of the spring dynamometer are equal, it means that the magnitude of the sliding friction force is independent of the magnitude of the motion speed of the wooden block; If the three readings are not equal, it means that the magnitude of the sliding friction is related to the magnitude of the motion speed of the wooden block.

Question 2: What are the three factors that affect the magnitude of sliding friction pressure; Coefficient of friction; Area. In general, there are only two factors that affect friction, pressure and coefficient of friction, because the area can be ignored in general.

And there are times when special cannot be ignored, so area is listed as the third factor. For example, the same weight of flat glass and column glass, on the glass plane, because the contact area of the plate is greater than the contact area of the column, the tension of the plate glass is not only not negligible, but also because it is greater than the column glass, so that the influence of tension on the friction force makes the area also an influencing factor.

Question 3: What factors are related to the magnitude of sliding friction Answer: 1. Make the wooden block move in a uniform linear motion.

Analysis: (1) When the pressure is constant, the rougher the contact surface, the greater the friction; When the roughness of the contact surface is constant, the greater the pressure, the greater the friction According to this, it can be known that the indication of the second and third spring scales should be greater than the first; (2) It is more difficult to do uniform linear motion with the spring dynamometer in hand, and we can make the spring dynamometer not move and pull the plank Solution: (1) According to the knowledge of friction, it can be known:

The second time is relative to the first, the roughness of the contact surface is certain, the pressure is greater, and the friction is greater; The third time is relative to the first, the pressure is constant, the contact surface is rougher, and the friction is greater So the experimental data of the first time is wrong; (2) make the wooden block move in a uniform linear motion;

Method: Keep the wooden block and the spring dynamometer still, and pull the wooden board under the wooden block to move Advantages: The wooden board does not have to move in a uniform straight line, the spring dynamometer is stationary, and it is easy to read the accurate indication Therefore, the answer is: (1) 1; (2) The answer is as described above

There are two factors that affect the magnitude of friction:

1. The magnitude of friction is related to the pressure between the contact surfaces, and when the roughness of the contact surface is constant, the greater the pressure, the greater the friction.

2. The magnitude of friction is related to the roughness of the contact surface, when the pressure is constant, the rougher the contact surface, the greater the friction.

The friction between solid surfaces is divided into sliding friction, rolling friction, static friction, rolling friction and rotational friction. In engineering, lubricants are used to reduce friction.

If two surfaces rubbing against each other are separated by a layer of liquid, then liquid friction can occur between them, and mixed friction can occur if the liquid is not completely isolated.

The air cushion guide rail uses gas friction to work, and the working principle of both lubricating oil and air cushion guide rail uses "friction with liquid or gas (i.e. fluid) instead of solid friction" to work.

It is related to the relative sliding velocity of the object in addition to the physical properties of the contact surface.

Sliding friction.

When two objects slide relative to each other (or have a tendency to slide relative to each other), a force that prevents the object from sliding will arise between the contacts, and this force is called sliding friction, or friction for short. The frictional force acts on the contact surface of the object in the opposite direction to the direction of the slide (or the direction relative to the sliding trend). According to whether there is relative motion between the contact surfaces, sliding friction can be divided into two categories: static sliding friction and dynamic sliding friction.

Generating conditions:

The contact surface between the two objects is rough.

Two objects are squeezing each other.

There is relative motion between objects or there is a relative tendency to slide.

Size:

With the same roughness of the contact surface, the magnitude of the sliding friction f is proportional to the positive pressure: f = n ( is the dynamic friction factor).

With the same pressure on the object, the rougher the contact surface, the greater the sliding friction.

The magnitude of the sliding friction is slightly smaller than the maximum static friction fmax. In the usual calculations, the maximum static friction can be considered to be equal to the sliding friction. Note: The sliding friction within a certain range is independent of the contact area; Sliding friction is independent of the speed of the object.

Nature:

1) The direction of the static sliding friction fs is opposite to the sliding trend, and the size of the friction is determined by the equilibrium condition.

2) The magnitude of the static sliding friction is a variable value, i.e. 0 fs fmax (the equilibrium range of the object).

3) Only when the object is in the critical state of equilibrium that will not move, the static friction fs reaches the maximum value, that is, fs=fmax=f·fn

Wherein: f - static sliding friction coefficient (no name).

fn — normal reaction force (also generally determined by the balance condition of the level and the annihilation).

Kinetic sliding friction: The frictional force that arises when an object has a relative sliding force is called dynamic sliding friction. The dynamic sliding friction is generally expressed by fd, fd=fn, where:

fn—normal reaction force; f—dynamic sliding friction coefficient. In the actual project, the rent width is f'It is not much different from f, so it is considered f'≈f。