Is static friction resistance or dynamic force

1. It can be either power or resistance
Power: when the bicycle is riding on sand or ice, the rear wheel will slip, so it is also sliding friction
when the conveyor belt rotates rapidly, keep the object on the conveyor belt. The object must have an acceleration, and the speed of the object must change from 0 to the same speed as the conveyor belt. Therefore, in this process, the object slips, so it is also sliding friction
no need to mention the resistance

2. Unknown_Error

3. No, it has to be for different objects. For example: a small object is placed on a large object, and a force is used to make the large object move. In case 1, the small object is stationary on the large object, and moves along the moving direction together with the large object. At this time, the static friction is the power for the small object and the resistance for the large object, The conclusion is opposite to the first one

4. For example, when a car is just started, the sliding friction of the goods is the same as the direction of motion, which is the power. The goods move at a uniform speed and are free from friction.

5.

Friction can not be regarded as power: it is said that when the wooden box on the truck accelerates with the truck, friction is the power for the wooden box to accelerate. We can see from the figure that: Taking truck B as the research object, under the action of power P, because wooden box a will proce friction KP under the action of gravity g, KP can not be the power; Similarly, when the wooden box a is taken as the research object, the inertial force F is the external force that causes the relative motion (no inertial force will cause the relative motion). At this time, the balance is the friction KF caused by the reaction force N, KF can not be called dynamic force. Moreover, KF is not necessarily equal to P. they are two completely different forces and cannot be confused. If we analyze the wooden box and truck as a whole, KP and KF are a pair of opposite internal forces, and they do no work to the outside world

for rolling power train, static friction is neither resistance nor power. It is an auxiliary force to stabilize the instantaneous center. Some people use the direction of static friction to judge whether it is rolling resistance or dynamic force, which is even more wrong. The direction of static friction is related to whether the rolling element is subjected to rotation or translation, so it is not the criterion of resistance and dynamic force. Attention

6. Friction can not be regarded as power: it is said that when the wooden box on the truck accelerates with the truck, friction is the power for the wooden box to accelerate. We can see from the figure that: Taking truck B as the research object, under the action of power P, because wooden box a will proce friction KP under the action of gravity g, KP can not be the power; Similarly, when the wooden box a is taken as the research object, the inertial force F is the external force that causes the relative motion (no inertial force will cause the relative motion). At this time, the balance is the friction KF caused by the reaction force N, KF can not be called dynamic force. Moreover, KF is not necessarily equal to P. they are two completely different forces and cannot be confused. If we analyze the wooden box and truck as a whole, KP and KF are a pair of opposite internal forces, and they do no work to the outside world
for rolling power train, static friction is neither resistance nor power. It is an auxiliary force to stabilize the instantaneous center. Some people use the direction of static friction to judge whether it is rolling resistance or dynamic force, which is even more wrong. The direction of static friction is related to whether the rolling element is subjected to rotation or translation, so it is not the criterion of resistance and dynamic force. Attention.

7. When the direction of friction is opposite to the direction of motion, it is mostly resistance, which is usually the case of pulling something on the ground
but when the direction of friction is the same as the direction of motion, it is power... For example, if you pull a box, a thing on the box also moves in the same direction.. this is power

8. Power: for example, conveyor belts and bicycles have more resistance, most of which are resistance. For example, the wood block is stationary on the inclined plane.
the friction does not change, but the effect is different

9. Resistance is the force that hinders the movement of objects. Friction is e to the relative motion or trend between objects. If the direction of friction is the same as that of motion, then it is the power. For example, conveyor belt

10. When two objects are superposed on the conveyor belt moving forward at a constant speed, when the two objects and the conveyor belt are relatively stationary, the static friction of the conveyor belt against the object below is resistance, and the static friction of the object above against the object below is power.