Is force friction

1. The friction force exerted on an object is the sum of all the friction forces exerted on the object.
it may be proced by one or more other objects.
for example, in real life, when a car moves, the friction force of the car comes from the air and the ground.
the friction force exerted by another object on a certain object indicates the person exerting and receiving the friction force.
for example, the friction force of the ground facing the car, The friction of air on the car
as for "for example, sometimes we encounter the problem that the friction of the table on the object, and then say that the object has different friction on other objects"
the friction of the table on the object, indicating that the force of the friction is exerted by the table, the object under force“ There is different friction between objects and other objects. "It is the object that applies the force, and it is the other object that bears the force, not the table. Of course, it is different from the friction between the table and the object.
for example, there is a sliding plate on the table and a roast ck on the plate. The table has friction against the plate, and the plate also has friction against the roast ck. The two forces are not the same, There are two different forces
it should be noted that the Z force of X on y is applied by X and applied by y

2. Force is the action between objects, all forces are forces, and friction is no exception. Friction always appears in pairs. There is friction f between a and B, and there is friction f between B and a;, F and F & # 39; They are acting force and reacting force.

3. Well, work is force × Displacement in the direction of force Force and displacement do positive work in the same direction and negative work in the opposite direction). If it is static friction, either the displacement is 0 and the work done is 0, or there is displacement and the displacement must be the same, so the amount of work done by the friction of the acting force and the reaction force is the same. If it is sliding friction, no matter what the reaction force is, the displacement of friction is always large, that is to say, the object that proces the force always moves a certain distance more because of relative sliding, because the work is equal to the force × So the absolute value of negative work must be greater than that of positive work. This is the key to the problem!!! In the functional relationship, the positive work makes the mechanical energy increase, and the negative work makes the mechanical energy decrease. If the work done by the friction force of the acting force and the reaction force is offset to zero, it has no effect on the mechanical energy. If the mechanical energy of sliding friction can be transformed into internal energy, the absolute value of negative work must be greater than positive work. The reason is what I said above.

4. When the object is stationary, the force is equal to the friction force
when the object is moving, the friction force is equal to the friction force μ* The pressure of the object on the supporting surface..

5. A pair of friction is not necessarily a force and reaction, whether it is a force and reaction depends on whether these points are satisfied:
1. Equal size, opposite direction, acting on a straight line
2. Acting on different objects
3 Disappear at the same time
4. The same property
the above four items must be met at the same time to confirm that a pair of forces are acting and reacting forces. The condition you give now only meets item 4: the properties of forces are the same, so it can't be determined

6. In this case, it is right: the object of action of force and friction is cattle, and if cattle do not move, it means that the resultant force is 0,
at this time, force = friction, so it is right in this case
this sentence is wrong when the object you are pulling is not moving at a constant speed. Because there's a part of the resultant force that provides acceleration. Force & gt; The friction has increased.

7. That's right. As you said, the principle of walking is to use the principle of action and reaction. When walking, people's feet push backward, resulting in the trend of backward movement, thus procing forward static friction, that is, people exert backward force on the ground, which in turn exerts forward force on people's feet, so as to help people move forward.

8. The friction on the ice is very small. When people push hard on the ground, the force will be greater than the maximum static friction, and they will fall.

9. Yes,
the nature of force and reaction force is the same,
If a force is elastic, its reaction force must also be elastic,
so the reaction force of friction must be friction

10. It' S hard to say.
friction comes from the interaction between atoms in contact with each other. When objects move relative to each other, the interaction forces will block the occurrence of the situation, thus creating a "resistance" to block the movement trend, which is also called friction. This is why if the contact surface is very smooth, the friction will be greater. If there is no external force, there will be no friction formed by the interaction force. From this point of view, friction is indeed a reaction force
from the perspective of force theory. Force occurs between two objects. There must be a forced object and a forced object, and the forced object is also a forced object. Of course, the forced object is also a forced object. When a person's foot rubs against the ground (when walking), the foot exerts a backward friction on the ground. However, it is also a stressed object. Therefore, if the ground is opposite, it will also give it a forward friction, so as to balance the two forces and prevent the foot from moving relative to the ground. However, when the human foot forces backward, there is no movement, but compared with the upper and lower body of the human body, joints can change the effect of the force, so that the center of gravity of the human body forward, so that the human body moves forward. Therefore, the friction force exerted by the ground on the feet is the reaction force exerted by the feet on the ground. The friction exerted by the foot on the ground is caused by the interaction of atoms.