High School Physical Belt Questions, About High School Physical Belt Questions

Heat generated by friction = sliding friction * displacement of the object relative to the conveyor belt.

The work done by the conveyor belt on the object = the heat generated by friction + the increase in the mechanical energy of the object.

The heat generated by friction + the kinetic energy of the object increases + the potential energy of the object increases.

Electrical energy = work done by the conveyor belt on the object + energy lost by the motor + energy of the conveyor belt.

Hope, thank you!!

It's best not to talk about electrical energy here, if you talk about electrical energy, it must be an ideal situation, that is, electrical energy is completely converted into mechanical energy and internal energy, respectively

When the above object is just put on, in terms of the system (motor, conveyor belt, above the object) conversion, it is the electrical energy that converts the internal energy and the kinetic energy of the above object. As far as the conveyor belt and the object are concerned: the two objects must slide relative to each other, the displacement of the conveyor belt below (constant velocity) is greater than that above, and the frictional work of the conveyor belt below is actually equal to the magnitude of the electrical energy dissipated, that is, equal to the increase in internal energy and the kinetic energy of the object above.

The difference between the work done by these two frictional forces is equal to the increased internal energy of the system, and the work done by the frictional force of the object above is positive work, which is equal to the increase in the capacity of the object.

The work done by friction provides kinetic energy to the object.

The increase in electrical energy provides energy to the conveyor belt to help accelerate the object to the same speed as the conveyor belt.

Discuss this question from the perspective of functional relationships.

The work done by friction w=f·s where f is the sliding friction force and s is the displacement distance, but this displacement is an absolute displacement, not relative, in this problem, the conveyor belt moves, the relative displacement between the small block and it becomes larger, but the displacement of the small block remains the same.

Therefore, regardless of whether the conveyor belt is in motion or not, the displacement of the frictional workmanship is always the length of the conveyor belt. So the friction workmanship size remains the same.

The speed at which the conveyor belt begins to slide remains the same, combined with the kinetic energy theorem, the workmanship remains the same, and the initial velocity of the flat throw when leaving the conveyor belt does not change, and the subsequent landing point does not change.

The reason why you choose B is because you don't fully understand what the work done by friction is going on, you have to know that the amount of work done by a certain frictional force on an object should be multiplied by the displacement of the object in the direction of this frictional force, not by multiplying the magnitude of this frictional force by the displacement of the object applying the force. For conveyor belt problems, you need to summarize and accumulate more.

a From the kinetic energy theorem: the object is only affected by friction and leaves the conveyor belt at a constant velocity.

You should think about the problem as a whole, in the process of the object and the conveyor belt, the friction force does not change, the work distance does not change, so the final result does not change. The work distance should be based on the ground.

Heat generated by friction = sliding friction * displacement of the object relative to the conveyor belt Work done by the conveyor belt on the object = heat generated by friction + increase in mechanical energy of the object = heat generated by friction + increase in kinetic energy of the object + increase in potential energy of the object = work done by the conveyor belt on the object + energy lost by the motor + energy of the conveyor belt is expected to be adopted!! Thank you!!!

Not contradictory. The magnitude of the acceleration is only related to the mass of the object and the resultant external force exerted. The force of a Ox can also produce a large acceleration, as long as the mass is small enough; A force of 10,000 N may also produce a small acceleration, as long as the mass is large enough.

What does a conveyor belt look like? Diagonal or horizontal? The oblique ones have gravity to do the work.

Level, this is not there...How does the heat generated by the system come from. Friction does the work, right?

Don't double-count. You don't have to think about how to convert energy, it's better to think about the work done by external forces, which can be clearer, and how to use these laws should be clear. 5 points ask someone to answer so much.

Not cost-effective. The test center probably has the shortest time to move on the conveyor belt, or what is the displacement of the distance with uniform acceleration, time, total time, and what kind of movement is done on the conveyor belt, etc., etc., there are too many, and Guangdong is unlikely to have a big problem. Isn't the relationship just how far the friction exists?

The friction must be parallel to the contact surface, if it is irregular (such as a gravel road, then it is another matter), if it is a diagonal upward conveyor belt moving clockwise, then you can understand it this way (I conveyor belt through friction to pull things up the trend of moving upward, no matter how fast you are, maybe the force you fall down is greater than the friction of the conveyor belt, but the tendency of the conveyor belt to pull up quickly exists), then it means that the friction is parallel to the conveyor belt diagonally upward.

As long as it follows the uniform speed of the conveyor belt, the force is balanced, and the direction of friction is always oblique upward.

The frictional force that rotates in a clockwise direction is to the left. The friction in the counterclockwise direction is to the right.

The amount of work done by the motor is equal to the electrical energy consumed by the motor; The work done by the conveyor belt is the increase in the mechanical energy of the block; The extra work done by the motor and the more electrical energy consumed by the motor are equal to the part of the internal energy generated by the sliding of the odorous block relative to the conveyor belt relative to the physical and conveyor belt when it maintains a relatively stationary motion.

After reaching the same velocity, the blocks will continue to accelerate evenly on the belt with a2=2 and v0=2, which is faster than the belt, so on the basis of the scratches (which slide backwards relative to the belt), they must also slide forward relative to the belt.

The displacement of the block in the second phase is 3m, which is determined by the displacement formula:

Find the time t=1s.

The displacement of the belt during this process.

x2=v0t2=2 m

The displacement of the block relative to the belt.

l2=x2 x2=3 m2 m=1m, so the trace length is δl2=1m

This 1m has the one that overlapped in the first stage.

During the whole process, the displacement of the block relative to the belt is.

The length of the trace we saw on the belt was 1m.

From the perspective of relative motion, in the first section, the speed of the conveyor belt is greater than that of the block, so the relative conveyor belt block moves backwards, and in the second section, the speed of the block is greater than that of the conveyor belt, at this time, the block moves forward relative to the conveyor belt, so the scratches will coincide during the movement of the two sections, and the longer section is L2 to calculate the final scratch length.

If you draw the diagram on paper, it will be clear.

AE represents the velocity graph line of the conveyor belt, and its acceleration is a = the coordinates of point E can be calculated as (4 3, 0). OC represents the velocity map line of the coal block in the first stage, and point C indicates that the velocity of the two is the same, that is, the coordinate of point C is (1, the coal block in this stage is drawn backward relative to the conveyor belt, and the length of the line is the area of AOC, which is 1m.

After constant velocity, the coal block advances, the sliding friction force is reversed, and the deceleration movement begins, because the conveyor belt first decelerates to 0, so the coal block has been decelerated uniformly to a standstill. CF represents its velocity graph line in the second phase. It can be found that the coordinates of point f are (2,0) and the area of the coal block with a length of CEF is 1 6m relative to the conveyor belt at this stage.

But the 1 6m is repetitively marked, so the coal blocks leave a 1m long scribing line on the conveyor belt.

From the above analysis, it can be obtained: a, b is correct and c is wrong, which should be the heat generated by the friction between the 2s coal block and the conveyor belt.

q=w=fs=μmgs= (1+1/6)=7/12 j<>

It is correct to say that as long as the object and the belt move in the opposite direction, then the frictional force is the same as the direction of the belt, because the frictional force always hinders the relative motion between the objects. When the object is just on the conveyor belt, the relative motion relative to the conveyor belt is the movement with a velocity of v1+v2 to the left, so the friction force is to the right to hinder this movement trend, so the direction of the friction force is to the right.

Calculate the total time from start to slide down (gravitational acceleration g takes 10m s2) Question adds: The answer I have calculated, s2 4 meters, visible blocks did not slide out of the conveyor belt. If you take the whole process as a stage.

This question is very typical, I won't give you the answer, I will tell you how to do it, otherwise you will not do it in the future. From the meaning of the title, it can be seen that after the slider slides down, the friction force in the AB section is unchanged from B to A (the friction force is related to the positive pressure, and has nothing to do with the direction of movement of the object), which can be obtained by S=AT squared, the friction is the same, A is the same, because the length of AB does not change, so whether AB rotates or not, the answer is the same, if AB rotates clockwise, the friction force is reversed, and the power becomes power, and the increase time of A is shortened.

The question is not clearly written! From the answer: the bevel is to the left of AB!

Regardless of whether the conveyor belt is stationary or rotates counterclockwise (clockwise, as long as the end velocity of the slider = speed of the conveyor belt) the answer is t1 = t2.

Because in the above case, the slider and the conveyor belt are in relative motion, and the force of the slider is the same by the method of sliding friction, so the movement of the slider is exactly the same, so t1=t2 is also inevitable!

Use the conservation of energy to do the friction to do the resumption of work.

There's no picture here, but it should look something like this:

1.The conveyor belt is left to right with a transmission speed of v1; Blocks move from right b to left with velocity v2;

2.Because there is only sliding friction at the level of the sliding process of the object, the acceleration (deceleration acceleration) a=f m=ug

3.The deceleration acceleration slows down the object, the object moves to the midpoint of AB l 2 distance, and the initial velocity v2 is known, according to the formula:

v2 square - vc square 2a=l 2 and a=ug can be found vc (velocity at the midpoint of ab) and t (time to point c);

4.Reaching the water level is considered in two situations:

The first is that the conveyor belt is not very long (the value of l is less than a certain range), and the object still has a leftward velocity greater than 0 when it decelerates to a, then this slides out of the conveyor belt, and the horizontal velocity at this time is the speed of the lower belt;

The second is that the conveyor belt is very long, and the object finally decelerates to zero, and then follows the transmission belt to the right and finally sends out from B, and the speed at this time can be known to be as large as the original incoming velocity v2 due to symmetry, and the direction is opposite.

This question is the first few hot test questions of Niu Er's law in the first year of high school, and the inclined conveyor belt is even more difficult, pay attention to the analysis of the force of various situations, to the speed of acceleration, and finally summarize to the actual motion. Hope it helps you ... Give me some points, landlord, I'm poor and crying.