Don t understand the difference between static friction and sliding friction?

Static friction also has two states of motion of uniform velocity and acceleration, how to distinguish them?

Actually, you can think of it this way.

Friction is generated between two objects and occurs when there is a tendency between two objects to change their state of motion.

For example, the cumtyh upstairs said, you are on the bus, it was originally stationary, but now the bus is leaving, and the people are stationary, and there is a tendency to change the state between them, so there is friction, and the result is that the car goes, and the people follow suit. This is a positive acceleration.

For example, when the bus and people are running at a constant speed, if the bus brakes, there is a tendency to slow down relative to people, and the friction against people at this time is deceleration, which is negative acceleration.

The landlord seems to be mistaken, the friction force and the object itself is not related, the so-called force is required to produce two objects, so the study of this force, to see the state of motion of two objects, not the state of motion of a certain object, the reason why static friction is static, that is, he is relative to the object that produces friction with it is stationary, that is, with an object as a reference, the other object is at rest, that is, there is no relative displacement, and if there is relative motion between the two, regardless of acceleration and deceleration,It's all kinetic friction.,The topic.,I'm now in the Department of Biology.,Don't study physics anymore.,I'm sorry.。

Sliding friction must be a fixed value, regardless of other conditions, as long as the object is moving on a flat surface, there must be sliding friction.

The value of static friction varies depending on the magnitude of the thrust. For example, if an object is at rest on a flat surface, an external force f is applied to it, and the object remains at rest. For the analysis of the force on the object, the upward support force and the downward gravity force are a pair of equilibrium forces, changing the magnitude of f, the object is still at rest, then the magnitude of the static friction force is always equal to f.

Static friction is created when there is a tendency for objects to move relative to each other, taking the most common example of inclined planes.

If the object slides down an inclined plane without an external force, then it is a sliding friction force, and the magnitude is n.

If the object is at rest on an inclined plane, then it is static friction.

Who said that static friction also has uniform velocity and acceleration, static friction is that there is no movement between two objects in contact, dynamic friction includes rolling and sliding, you search for what static friction is, take a closer look.

Look at whether there is relative motion between the objects in contact", "there is sliding friction, and there is no static friction." Well, I can only solve the problem myself, and I can't teach it.

The maximum value of static friction is greater than that of sliding friction, while the magnitude of static friction and sliding friction cannot be compared.

The magnitude of the static friction force will change, and the magnitude of the tensile force is equal to the size of the tensile force, and the greater the tensile force, the greater the static friction.

The sliding friction is constant, which is related to the roughness and pressure of the contact surface.

Sliding friction = dynamic friction factor * positive pressure between objects.

The difference between static friction and sliding friction is that static friction is the force experienced by a stationary object, which has a relative sliding tendency but does not occur relative sliding. Whereas, sliding friction is the relative slip that has taken place.

Friction: Friction is related to objects rubbing against each other, so the description of friction in physics is not generalized and not as precise as other forces. Without friction, shoelaces cannot be fastened, and screws and nails cannot hold objects in place.

The biggest distinction within friction is between static friction and other frictional forces. Some people believe that static friction should not actually be counted as friction. All other frictional forces are related to dissipation: it reduces the relative velocity of objects rubbing against each other and converts mechanical energy into heat.

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 also occur if the liquid is not completely isolated.

Static friction:

Static friction is when two objects in contact with each other are relatively stationary, but there is a tendency to relative motion, a force will be generated between the contact surfaces that hinders the relative motion, and this force is static friction.

Definition: When an object moves on the surface of another object in the tangential direction of the contact surface or has a tendency to move relatively, a force that prevents their relative motion or tendency to move relative to each other occurs between the contact surfaces of two objects, and this force is called friction.

If two objects are in contact with each other and squeezing each other, and the objects are relatively stationary, if they only have a clear and cautious relative sliding tendency under the action of external forces, and no relative sliding occurs, the force that prevents the relative sliding between their contact surfaces is called "static friction".

1. The causes are different.

If two objects that are in contact with each other and squeezed each other, and are relatively stationary, if they only have a relative sliding tendency under the action of external forces, but do not slide relatively, the force that prevents them from sliding relative is called "static friction". When static friction occurs two objects are at rest relative to each other.

Sliding friction is the force generated between two objects with relative sliding on the contact surface that prevents them from sliding relative to each other. Sliding friction requires relative motion.

2. The direction of the force is different.

The static friction force is always opposite to the direction of the relative movement trend, and is not necessarily tangent to the contact surface, which can be judged by the equilibrium method. It can be a drag force or a driving force, and a moving object can also be subjected to static friction.

The sliding friction is always tangent to the contact surface and opposite to the relative direction of motion of the object.

3. The magnitude of the force is different.

The maximum static friction is greater than the sliding friction and the rolling friction is much smaller than the maximum static and sliding friction.

1. Static friction is the obstruction of an object by another object when it has a relative motion tendency on the surface of another object.

2. Sliding friction is the force generated on the contact surface between two objects with relative sliding that hinders their relative sliding, generally speaking, the friction generated when an object slides on the surface of another object.

Sliding friction, as the name suggests, is only found in relative sliding, and magnitude = uf(f pressure).

Static friction, two objects that are relatively stationary and have a relative tendency to slide, the magnitude is equal to the external force.

Maximum friction, when the thrust given is greater than the maximum friction, the object is pushed, and then it becomes sliding friction, and the magnitude of the maximum friction is proportional to the pressure given.

The maximum static friction is only a little larger than the sliding friction, which is basically equal when used as a lifting shed, and equal in high school physics. As for why, it is because objects have inertia, and so do stationary objects, so force is needed to overcome the inertia of the object, which causes the maximum static friction to be greater than the sliding friction.

Friction is caused by the interaction between noisy molecules on the contact surface of two objects that interact with each other and weigh each other. The greater the elastic force between two objects, the smaller the distance between the molecules, and the stronger the interaction force, the greater the external force that makes one object move relative to another. This is the reason why the maximum static and sliding friction are directly proportional to the forward and backward forces, and the molecular state, properties, and temperature of the contact surfaces of the two objects all have an effect on the friction force.

From a microscopic point of view, the interaction time of molecules in the state of maximum static friction and sliding friction is quite different, and there are the following three differences.

1.Molecules that have been in contact with the surface for a long time wriggle under elastic force, which increases the contact area of the contact layer molecules.

2.Due to long-term contact, the thermal movement of the molecules causes the contact surface layers to diffuse each other, thus increasing the intermolecular forces.

3.The surface of the object is covered with a contaminating film. When the external force macroscopically does not move, the molecules in the contact layer will move by the order of magnitude of the certified molecules, resulting in the rupture of the polluting film.

When the objects that are in contact with each other and have a relative sliding tendency to squeeze each other, the frictional force generated between the objects is called static friction. The conditions are that two objects need to be in direct contact, in contact with each other and squeezed to dig the racket, there is a tendency to move relatively, and the contact surface is rough.

The frictional force that occurs when two touching objects are in a critical state where they are about to slide but have not yet slided. At this point, the frictional force of the touching object reaches a maximum value. It is contrary to the direction of the force that causes the object to move in a direction, and its magnitude is proportional to the magnitude of the positive pressure (i.e., the normal reaction force) n between the two objects.

If there is sliding friction between two objects in contact with each other, there must be relative motion between the two objects; The point of action of the sliding friction force: on the surface where two objects are in contact with each other. Direction of sliding friction:

Tangent to the contact surface, opposite to the relative direction of motion between objects. Finch sedan chair.

The difference between maximum static friction and sliding friction is that the former is relatively stationary between the two objects, and the contact parts act for a long time. The latter is a relative motion between two objects, and the action time between fixed points on the two objects is short.