If the thin line 1 is changed to the same length, the light spring with the same quality, the other conditions are unchanged, and the steps and results of the solution are exactly the same as the one, that is, the analysis considers the deformation of the front line from the actual situation is not obvious, can be ignored Cut the shape of the instantaneous line to recover time. Ideally, the elastic force of this rigid body is synchronous with the change of other forces it receives. It is a catastrophic process from rest to motion, and the process is almost time-consuming to pass.
In summary, I know that the result of this classmate's solution is wrong, because the line force on 1 has changed immediately, but he thinks that after cutting the 2 lines, we can also analyze the non-deformable objects such as lines. It is a quasi-rigid body. If it is considered that the quasi-rigid shape recovery needs a period of time, that is, it will maintain the original state, then we may give an example to verify that the reliability of this model has a hole with a slightly larger radius. The light paper sticks to cover the hole, and then the ball of the mass radius is placed in the center of the paper, and the tension of the thin wire hanging the frame at rest is 2 〃. Then use the fire to burn off the light paper. If it takes a period of time to recover from the shape of the quasi-rigid body, that is, it will maintain the instantaneous assumption that the tension of the suspension line will be maintained at =2, and the frame will get a 6; . But experiments have shown that this phenomenon does not exist.
We can also improve the analysis of the tension changes. It really needs to go through a very short transient. In this moment, the Song velocity is zero, the normal acceleration is zero, the acceleration is tangential acceleration, and it can be along the normal along the rope and cut. The coordinates are established in two orthogonal directions, the tangential force is the center of the heart, and the ton is 0 = coffee cut =! 0, so 2 = along 7; the acceleration of the object being lifted from the skin training, the tension at the moment of the transition and the acceleration of the suspended object are rapidly changing, and the value between them is uncertain. In elementary physics, we should condense this momentual idealization into a single moment. In fact, such simplification is not inconsistent with the actual situation. The answer to the first one should be that the result of the second case is correct, because the length of the spring is at the moment of cutting, and it can be considered that it has not yet changed, its recovery time is obvious, and the thin line There are essential differences.
The open thinking of the spring class Gao Wang Zhendong, Shaanxi Province Yongshou County Middle School 713400 conditions open to suspend according to the way, now requires the total length of the two springs, for example, the 5132 stiffness coefficient is large, it should be like two springs, 12, The heart quality is 5 on the top. above.
The two small objects for the ceremony and the call are called the spring and the object 851 on the top. 52 is on, 2 is on.
That is to say, the small ball and the big ball repeatedly contact, so that the small ball potential is equal to 70, the small ball has the largest amount of electricity, so the big B is small, and the spring between the 0 small is regarded as a whole. Because 蚣 =, + call the heart to make the upper spring stretch is large, it should be suspended at the top. Isolation of the lower object, because the bottom spring should be maximally extended, the object should be hung at the bottom, and the above analysis is combined. The answer is 2. The vertical smooth rod has a small ball and two springs, and the ends of the two springs are respectively Connected to the small ball, the other end is fixed on the rod with the pin è‰, the small ball, from the static state, set the technology to the pin, the acceleration of the ball is 12, if you do not remove the pin and pull the pin In an instant, what is the acceleration of the ball? The Shanghai solution can be reasoned based on the various states of the spring.
When the two springs are in the extended state, the force of the ball balances 3 and the spring force of the upper and lower springs respectively.
When the two springs are in the compressed state, the ball is balanced by the force.
When the pin is removed, if the root of the NM+mg spring is elongated and the root is compressed, the ball cannot be balanced, which means that the ball cannot produce an intentional acceleration.
It is connected with two springs of A and B. The stiffness coefficient of the two springs connected to the lower end of the B spring is the upper end of the current hand armor, so that it moves up slowly. When the B spring is separated, the analysis is based on Hooke's law. The shape variables of the two springs of the armor and the B are solved according to the relationship between the shape variable and the 4-point moving distance. Since the later state of the B spring is stretched or compressed, it is not described in the case, so it should be studied in two cases.
The B spring is originally in a compressed state, and its compression amount is =, when the pull arm is slowly moved up, the B medium elastic force is reduced to the original 4 o'clock.
1 B is still in the compressed state, then the elastic force and elongation of A are respectively the upper end of the B spring, so the distance of the end up is 2 B is stretched, then the elastic force and elongation of A are respectively For the upper end of the B spring, the distance between the 4th and the 4th end is shifted. The overall method is to regard the springs A and B as the whole series in series. The stiffness coefficient is that when the spring B is in the compressed state, the pulling force is Corpse =, so the end moves up to each other = å“©, when the B spring is in tension, the upward pull star! X. In nuclear physics, the most effective way to study the relationship between nucleons and nucleons is that the first half of the reaction of the two-charge exchange reaction is similar to the mechanical model described below. The two balls and the 3 are connected by a light shield spring and are stationary on a smooth horizontal straight track. On their left side there is a fixed baffle perpendicular to the track, on the right there is a small ball along the track at a speed of 5 balls, 6.0 and 5 collide and immediately form a whole in the process of their continued leftward movement, when the spring length When it is changed to the shortest length, the length is suddenly locked and does not change. Then, the ball collided with the baffle corpse, and after hitting it, it was still, and it was in contact with the corpse without sticking. After a while, there is no mechanical energy loss due to sudden unlocking and unlocking. It is known that the quality of 30 balls is all.
Find the speed of the ball after the spring length has just been locked.
2 seeking. 4 The ball leaves the baffle, and the maximum elastic potential of the spring during the subsequent movement.
The analysis only interacts with a dynamic open cycle and a recurring cycle.
The ball collides with the 8 ball and immediately forms a whole. The process is extremely short, and the spring is conserved for momentum without the elastic ball and 3 balls.
0 moves the compression spring to the left to make the spring generate elastic force. Under the action of the elastic force, 4 starts to accelerate from the static; the spring elastic force is the resistance, so that the speed starts to decelerate, there is always an instant, the speed reaches the phase, then the spring is Compress to the shortest.
After the lock is released, under the action of the spring force, 4, the acceleration movement starts. When the spring returns to the natural length, in the subsequent movement, the deceleration motion is made to the left under the action of the elastic force, and the deceleration motion is made to the right when the 40 speeds are equal. When the length of the spring is the longest, the elastic potential is the largest. After the 4 balls and 0 balls complete the cycle change, then the above change process is repeated. In the above process, the momentum and mechanical energy of the system are always kept constant. When the solution is set to stick to the stone ball, the speed of 0 is 1. The momentum is conserved. When the spring is pressed to the shortest, the speed is equal to the speed of the sense. This speed is still. By the conservation of momentum, there is a speed v22 obtained by the two equations. After the spring length is locked, the potential energy stored in the spring is. Conserved by energy. After the impact of the body, the kinetic energy of 4 and 1 is zero. After the lock is released, when the spring returns to the natural state, the potential energy is completely converted into the kinetic energy. If the speed is set to milk, then the spring will be extended, and the 4 balls will leave the baffle and obtain the speed.
When the speed is equal, the spring reaches the longest. When the speed spring at this time is extended to the longest, the potential energy is large, and the potential energy is set. Conserved by energy, there are solutions to the above formulas. 3. Solve the choice of physical selection.
In the oAc, the rectangular uniform magnetic field region is 6=2, and the magnetic field direction is perpendicular to the paper surface; the solid line frame 7 is a square wire frame, and the 6 sides are parallel to the 6 sides. If the wire frame is pulled away from the magnetic field region at a constant speed to pull out the work done by the external force in the direction parallel to 6, the ash 2 pulls the work done by the external force in the parallel direction in the direction parallel to the direction, The wire frame pulls out the kinetic energy at a constant speed. It is known from the conservation of energy that the work done by the external force is converted into Joule heat.
When the wire frame is parallel and pulled out in the 6 direction, when the wire frame is pulled out in the parallel direction, the ideal transformer is excluded. The number of turns of the primary coil and the secondary coil are respectively Yang and 2. The input and output voltage and current power are respectively during normal operation. For recognition of 1 and 21 and corpse 2. Known m12, W solution Because the ideal transformer does not consider power loss, then, 1 equivalent method test 9 slender light rope æ‹´ small ball constitutes a single connection, directly below the suspension point + There is a hitch in the length of the pendulum that can block the cycloid. 9. Now the single is connected to the left to open a small angle, and then there is no initial velocity release for the following movements. The single pendulum cycle is small when there is no nail.
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