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Anonymous users2024-02-09The first belongs to rolling friction, the essence of rolling friction is to produce a drag moment, that is, the support force of the ground is no longer directed to the axis of the wheel, but there is a forward offset in one direction, this offset produces a moment that hinders the rotation of the wheel, making the rotation slower, if the wheel and the horizontal plane are ideal rigid bodies, if they do not deform, they are not subject to rolling friction and move forever, even if the contact surface is rough.
The friction of the sandpaper on the table does not do work, because the table does not move, but the paper does negative work on the friction of the sandpaper, which produces internal energy.
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Anonymous users2024-02-081.The axle is smooth enough to indicate that its own rotation does not lose energy, the rough wheel and the ground indicate that the forward will consume kinetic energy, w=fs, f=f, s is the displacement, and the trolley will slow down until it stops.
2.Sandpaper does work on the friction force of the desktop, the principle is the same as above, w=fs, the friction is strong and displaced.
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Anonymous users2024-02-071 The trolley slows down because the table top has friction against the wheels.
2 The sandpaper does not work on the friction force on the tabletop because there is no displacement of this force. However, the friction of the table top on the sandpaper is displaced, and the size is f*s, which is exactly the amount of heat generated by friction.
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Anonymous users2024-02-061. Decelerate with constant acceleration until the velocity becomes zero. It is a gradual stop.
2. If no work is done, w=fs, and s=0, then w=0.
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Anonymous users2024-02-051.Yes. There is no relative motion, but there is a tendency to relative motion, which also produces friction 2
The conditions to be met to propel an object: the thrust is greater than the maximum static friction of the ground against the object3Stationary state:
The thrust must be greater than the drag, otherwise it cannot be pushed. State of motion: A force equal to the drag force allows the object to continue to move, otherwise the object will slow down until it stops.
4.An object is pushed from a resting state, and the thrust is greater than the drag force at this stage, and the object accelerates and accelerates. If an object is not in equilibrium, it is naturally not in a state of equilibrium.
When the object is moving, if the thrust is reduced to equal to the drag, the thrust and drag force are balanced. The object moves in a straight line at a uniform speed, and the object is in equilibrium and the state of motion remains unchanged.
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Anonymous users2024-02-041.Does the relative motion of the object produce friction - will it be generated - because friction is divided into two categories, one is called static friction - that is, when the object is relatively stationary, but there is a tendency to move, this friction is always balanced with the external force before reaching the maximum!
2.Why is it that the force is small and the object cannot be pushed, and the force is large and the push can be moved - when the thrust is less than the maximum static friction generated by the object, the object is subjected to a balanced force - [static and static], so what conditions are met for the force required to push an object? - Push when the thrust is greater than the maximum static friction - make the force on it unbalanced, so that the motion of the object changes!
3.Does the thrust that pushes an object have to be equal to the frictional force (or various resistances), that is, the thrust is equal to the drag? - Yes when the object is at rest, and when the object is in motion, and it is moving in a straight line at a uniform speed! When the thrust is greater than the drag, the motion state of the object changes.
4.When an object is pushed from a state of rest, then the balance of the two forces disappears - correct, if it is still balanced, the state of motion of the object will not change - [the static is constant], the resistance is not generated at the same time as the thrust, the magnitude is equal, the direction is opposite, in a straight line, acting on an object, then the state of motion of the object does not change? - Kinetic friction resistance has nothing to do with thrust!
Thrust and drag don't always occur at the same time – static friction sometimes occurs at the same time, not always! - When the object is in motion, the thrust and resistance are equal and the direction is opposite, and when it acts on an object in a straight line, the state of motion of the object does not change!
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Anonymous users2024-02-031. Depending on the situation, sometimes there will be static friction, and there is no friction when placed in a horizontal place, and there is friction on the slope.
2. Thrust is greater than friction.
3. If not, if it is not pushed, it is equal, if it is pushed, the thrust is greater than the resistance 4, the two forces in the horizontal direction are balanced, the vertical direction does not disappear, the thrust is not necessarily equal to the resistance, if it is equal, the object does not change the state of motion, and the thrust is greater than the resistance will change.
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Anonymous users2024-02-021.Not necessarily, objects are only subject to friction when they are in relative motion or have a tendency to move relative (pressure on rough contact surfaces), where relative motion corresponds to sliding friction (or rolling friction) and relative motion tendency corresponds to static friction. 2.
As long as the object is still at rest and is subject to thrust, i.e., it has a tendency to move relatively, it will be subjected to static friction, and the applied thrust must be greater than the maximum amount of static friction in order for the object to be propelled. 3.No, only if the object is in equilibrium, the thrust will be equal to the drag.
4.First of all, the resistance of the object at the moment of being pushed is the maximum, that is, the maximum of the static friction force is reached, when this maximum is exceeded, the object will be pushed, at this time the balance of the two forces disappears, the object is in a state of motion, if the thrust is reduced to the same size as the sliding friction force, the balance of the two forces will appear, otherwise there is no balance of two forces. The so-called drag equals thrust only in equilibrium, and it is true that both occur at the same time.
Since the amount of resistance generally does not change in the state of motion, the state of motion of the object will only change when the magnitude of the thrust changes. (If you still have any questions, please feel free to ask).
This question should be considered in two processes:
1.Because when only F1 is added, the object moves in a uniform straight line to the east, so the sliding friction is 10N to the west, remove F1, and add F2 until the object velocity is 0, the object velocity direction remains unchanged, so the sliding friction of the object is still 10N to the west. >>>More
It's not hard to figure this out.
In the case of straight pulling, the tensile force f1=umg=f used to reach the critical state, where u is the critical static friction coefficient, m is the cement mass, g is the gravitational acceleration, and f is the maximum static friction. >>>More
The generation of rolling friction is caused by the deformation at the contact point between the object and the plane. The object is pressed into the bearing surface by gravity, and at the same time it is also deformed by compression, so when rolling forward, the bearing surface in front of it is uplifted, which makes the point of action of the elastic force n of the support facing the object move forward from the lowest point, so the elastic force n and gravity g are not in a straight line, but form a force couple moment that hinders rolling, which is rolling friction. The magnitude of rolling friction is measured by the coupling moment, and is proportional to the positive pressure, and the proportional coefficient is called the rolling friction coefficient δ, which is numerically equivalent to the elastic force to the force arm of the center of mass of the rolling object, so it has a dimension of length; It is related to the material, hardness and other factors of the rolling object and the bearing surface, and has nothing to do with the radius. >>>More
1.If there is no extrusion between objects, there is no friction, that is, a stationary wooden block on a horizontal table is not affected by friction; >>>More
It's because there is static friction when it's stationary and sliding when it's sliding, and the two frictions aren't the same, and the maximum static friction is the same as sliding friction (note that static friction is not a fixed straight, but sliding friction is straight.