Is the friction on the bottle in your hand 0?

The wooden block is subject to static friction in the process of moving from rest to motion, and static friction only works when it is relatively stationary. When it moves relatively, it is the kinetic frictional force. When you hold the bottle in your hand, the bottle is subjected to the gravitational force given by the earth, and if there is no other force, the bottle will move downward, so the reason why the bottle is still is due to the static friction force given by the hand.

According to Newton's law, the weight is stressed in this process, because it is relative to the wooden block, so it is subjected to the static friction given by the wooden block, and the force is not 0.

When the weight enters a uniform linear motion, according to Newton's law, the weight is not stressed in the horizontal direction at this time, so the static friction force is 0.

That is to say, the weight is subjected to a static friction force that is not 0 in the process of moving from rest to motion, and when the weight enters a uniform linear motion, the static friction force is reduced to 0.

Force Analysis Suppose there is no friction, then he is subject to only one gravitational force, according to Newton's second and third laws, the bottle will move downward with acceleration g, but it is stationary, so the assumption is not true, so he is subjected to friction, and the magnitude is equal to gravity, so that the net force is zero, according to the ox, he is at rest.

Upstairs, if the bottle is on the ground, ignore the gravity of the bottle.

Well, if you ignore the amplitude of the hand going up and down with the beating of the heart, you can also think of it as a stationary situation.

Is there still friction.

No, it is subject to static friction, which is equal to the gravity of the bottle.

Summary. Hello dear. We'll be happy to answer for you.

Holding the bottle with your hand is subjected to static friction, but why is there no elastic force. When the bottle is at rest, it is the static friction force, and the static friction force should be analyzed by the equilibrium condition, and has nothing to do with the elastic force Their point of view is wrong Because the bottle is subjected to static friction when it is stationary, the static friction force experienced by the bottle is balanced with the gravity of the bottle, which remains unchanged, and has nothing to do with the force of the hand and the dryness and roughness of the hand Comment The static friction has nothing to do with the pressure, it changes with the change of external force, here the grip force becomes larger, but the maximum friction force becomes larger, and the static friction of the object remains the same Friction: The force that hinders the relative motion (or relative tendency of motion) of an object is called friction.

The direction of frictional force is opposite to the direction of the relative motion (or relative tendency of motion) of the object. There are three types of friction: static friction, rolling friction, and sliding friction.

Hello dear. We'll be happy to answer for you. Holding the bottle with your hand is subjected to static friction, but why is there no elastic force.

When the bottle is at rest, it is a mountain of static friction, and the static friction should be analyzed by the equilibrium condition, and has nothing to do with elasticity Their point of view is wrong Because the bottle is subjected to static friction when it is at rest, the static friction force of the bottle is balanced with the gravity in the bottle collapse friend from the equilibrium condition, which remains unchanged, and has nothing to do with the force of the hand and the dryness and roughness of the hand Comment The static friction has nothing to do with pressure, it changes with the change of external force, here the grip force becomes larger, but the maximum friction force becomes larger, and the static friction of the object remains unchanged Friction: The force that hinders the relative motion (or relative tendency of motion) of an object is called friction. The direction of friction is opposite to the direction of the relative motion of the object (collision or relative tendency of motion).

There are three types of friction: static friction, rolling friction, and sliding friction.

Isn't this a contradiction with friction and elasticity?

Hello dear. We'll be happy to answer for you. Causes of elasticity:

There is not necessarily an elastic force between the objects in contact with each other, and only when the two objects are squeezed or stretched by each other and deform, because the object wants to return to its original state, the elastic force is generated on the object in contact with it at the position of the contact bend. The direct cause of the buried elastic force is the deformation of the force object and the return to its original state. The main thing is that the object needs to be deformed to have elastic force involved.

There is no elastic force, why is there static friction.

Hello dear. We'll be happy to answer for you. There is no elastic force, why is there static friction in the friend?

Holding the bottle in your hand, the bottle moves downward due to gravity, and the frictional force prevents the bottle from moving downward, which is the friction that the bottle is subjected to, which is opposite and equal to the direction of gravity. Friction: The force that hinders the relative motion (or relative tendency of motion) of an object is called friction.

The direction of friction is opposite to the direction of the relative motion (or relative tendency of motion) of the mass mountain object. There are three types of friction: static friction, rolling friction, and sliding friction.

Hello dear. The key is whether the bottle has been deformed. Without deformation, there is no elastic force involved.

This is the knowledge of equipoise.

Look at the force analysis diagram.

At this time, the static friction and gravity are balanced, and they have nothing to do with the horizontal pressure, which is what you call the grip force, and the gravity does not change, so the friction force does not change.

Because the friction force is static friction at this time, its magnitude has nothing to do with the pressure, and according to the knowledge of the two-force balance, it can be seen that its magnitude is always equal to the gravitational force. The pressure and roughness of the contact surface that you have learned are just the factors that affect the sliding friction.

There is no relative motion (the position of the hand pinching the bottle is not the same), and the friction and gravity are equal.

Increase the grip on the bottle held in the hand, the bottle is held in the vertical direction in the air with the hand, then the hand grip on the bottle is in the horizontal direction, and the bottle in the horizontal direction of the hand does not produce movement relative to the hand,

Unchanged gets bigger.

The bottle is always at rest, according to the knowledge of equilibrium: the static friction of the bottle by the hand and the gravity of the bottle itself are a pair of balancing forces. When the bottle's own gravity changes, the amount of static friction changes.

The bottle stall is trapped to remain stationary, and the balance of the bottle is envied, and the force analysis of the bottle is that the vertical direction is subject to gravity and static friction, and the two forces are balanced, so the static friction is equal to gravity;

After doubling the grip force, the bottle can not fall off, it still remains stationary, and the gravity and static friction in the vertical direction are still balanced, and the static friction is still equal to gravity;

Therefore, choose B

That's right. Because of the maximum static friction.

It is proportional to the positive pressure experienced by the contact surface.

The tighter the hand, the greater the positive pressure on the contact surface between the hand and the bottle, and the greater the static friction.

However, the static friction of the hand against the bottle remains the same, or Bi Yin is equal to the gravity g of the bottle, so the number of leads, the tighter the hand, the heavier the object can be held.

g（max)=f(max)

a. The heavier the bottle, the greater the friction on the bottle, because the friction is balanced with gravity, A is wrong, B is correct;

c, the bottle remains stationary, the force is balanced, the force analysis of the bottle is sold and rented, the vertical direction is subject to gravity and static friction, and the two forces are balanced, so the static friction bucket force is equal to gravity, the tighter the hand, the greater the maximum static friction between the oil bottle and the hand, but the static friction remains unchanged, c is a positive omen, d is wrong;

Therefore, I chose: BC

Xiao Ming held a bottle with his hand, the mass of the bottle remained unchanged, and the gravity remained unchanged

If the grip force is increased, the bottle is still still in the hand, and the vertical direction of the bottle is subjected to the vertical upward friction and the vertical downward gravity, the gravity remains unchanged, and the Mohs land friction force remains unchanged

Therefore, choose D