Friction is resistance
people, bicycles, cars and so on move forward by friction. The direction of friction is the same as the direction of motion. At this time, it is not resistance but the driving force to move forward.
when braking, friction becomes resistance. Amitabha!
The only difference between resistance and friction is the concept
The force that hinders the relative motion or the trend of relative motion of an object is called frictionwhen one object slides on the surface of another, friction between contact surfaces hinders their relative motion, which is called sliding friction. The sliding friction is related to the roughness of the contact surface and the pressure. The larger the pressure is, the rougher the contact surface is, and the greater the sliding friction is
Resistance is an effective force. It can be simply understood as: the force that prevents physical movement is called resistance, and the force that promotes the movement of an object is called power. Resistance and power are antonyms of each othera train running on a straight railway is subject to the traction of the locomotive and the resistance of the air and the rail at the same time. The direction of traction and resistance is opposite, traction makes the train speed increase, while resistance makes the train speed decrease. If the traction and resistance balance each other, their effects on the train will cancel each other, and the train will keep moving in a uniform straight line
The characteristics of friction force are related to the objects that rub each other. Therefore, the description of friction force in physics is neither general nor accurate as other forces. Without friction, shoelaces can't be fastened, and screws and nails can't hold objects The biggest difference in friction is between static friction and other friction. Some people think that static friction should not actually be counted as friction. Other frictional forces are related to dissipation: it reces the relative velocity of objects that rub against each other and converts mechanical energy into heat energyan object moving relative to a fluid is resisted. This resistance is in the opposite direction of its motion. In the case of laminar flow, the resistance is proportional to its velocity. In turbulence, the resistance is proportional to the square of its velocity
sometimes an object is subject to resistance and friction at the same time, for example, a car is subject to both air resistance and rolling friction of its tires when it is moving Friction sometimes makes objects move, unlike resistance.)
Second, resistance e to the viscous effect of air, the surface of the object will proce friction tangent to the surface of the object, and the resultant force of all friction is called frictional resistance. The pressure difference resistance is the resistance formed by the airflow pressure perpendicular to the object surfacewithout considering viscosity and wake vortex (see lift line theory), the pressure drop of the body in subsonic flow is zero (see d'Alembert paradox). In the real fluid, the viscosity will not only proce friction resistance, but also make the pressure distribution on the surface different from that in the ideal fluid, and proce pressure resistance
Definition of friction:
the force that hinders the relative motion or the trend of relative motion of an object is called friction
Resistance is an effective force. It can be simply understood as: the force that prevents physical movement is called resistance, and the force that promotes the movement of an object is called power. Resistance and power are antonyms of each other the difference between the two is that friction may become power (for example, the upward friction of rock climbing enthusiasts). In fact, when the friction on the object is opposite to the direction of the object's movement relative to the ground, it is resistance, and when the direction is the same, it is power there are more forces that can act as resistance. Thrust, pull, elasticity and friction can all be resistance
friction refers to the force that hinders the relative motion (or relative motion trend) of an object. Its direction is opposite to the relative motion (or relative motion trend) of the object
friction is divided into static friction, rolling friction and sliding friction. The sliding friction is related to the roughness of the contact surface and the pressure. The larger the pressure is, the rougher the contact surface is, and the greater the sliding friction is
there are two essences of friction between solid surfaces: the mutual attraction (glue force) between molecules on solid surfaces and the mechanical occlusion caused by their rough surfaces. The sliding friction is always smaller than the maximum static friction. It consists of the pressure FN perpendicular to the friction surface and the sliding friction coefficient μ It is independent of the relative velocity and area between sliding surfaces. The friction coefficient is determined by the material, roughness and (possibly) lubricant of the sliding surface
friction is not necessarily resistance, it may also be the driving force to make objects move. It should be clear that the objects in contact are the reference objects to block the "relative motion"“ "Object motion" may refer to other objects. For example: in life, the conveyor belt to the goods from the low to the high, is to rely on the conveyor belt to the goods oblique upward friction.
the following examples are respectively:
equal time: rough peck on the moon, push the object with a horizontal thrust, and the object moves at a uniform speed
when not waiting: for example, the car moves up a rough slope. The resistance at this time is actually composed of a downward component of the gravity of the car along the inclined plane and the friction of the inclined plane This may not have been learned in junior high school, but understand)
when friction is the driving force: when the belt is conveying an object, it just puts the object on the belt. At first, the initial velocity of the object is 0, and then the object accelerates under the action of friction
for the above two situations, you can make an understanding.
I'll give you an example of each of the four situations mentioned above, and you'll understand
1. Friction is resistance: as we all know, when a car is driving on the road, the friction between the car and the ground is resistance
2. Friction is the driving force: a wooden block is placed on the table. When we push the wooden block with enough force, it may happen that the wooden block drives the table forward together. At this time, if there is relative displacement between the wooden block and the table, there will be sliding friction between them. If there is no displacement, there will be static friction. That is, there is friction between the block and the table. And this friction, relative to the table, is power. Because it's the friction that drives the table
3. Resistance is friction: in this case, needless to say, the resistance of the wooden block to the sliding table is the friction between the wooden block and the table
4. Resistance is not friction: when the block moves on the plane, it will stop when it touches the wall. At the moment when the block stops, if the block changes from speed to no speed, the block will stop e to certain resistance, which is not friction, but the thrust of the wall on the block.
give an example to help understand: AB two non smooth objects stacked together, a in a non smooth plane, under the force F to push a, AB at the same time forward for uniform motion. Analysis: the force between a and plane, a to B, B to a
obviously: between a and the plane, the plane proces friction force on a, which constitutes the friction resistance of a movement, the magnitude of which is equal to the force F, and the direction of which is opposite; The friction force ABF makes b move forward in the same direction as the force F, and its magnitude is equal to the friction force B exerts on a; The friction force BAF is equal to that of ABF, but opposite to that of ABF.