How to calculate the force of a hard moving pulley

1. The pulley can be regarded as a deformed lever. The so-called labor-saving and distance saving are based on the lever principle (that is, F1 * S1 = F2 * S2). When the force F of the movable pulley acts on the rope and the weight g to be lifted is hung on the movable pulley, the arm of force F is the diameter of the movable pulley, while the arm of weight g is the radius of the movable pulley, so g = 2F
when the force F of the pulley acts on the movable pulley and the weight g to be lifted is hung on the rope, the arm of the force F is the radius of the movable pulley and the arm of the weight g is the diameter of the movable pulley, so f = 2G
to save the distance, a single movable pulley has a rope on the left and right. If the movable pulley raises the height of L, the rope on the left and right sides of the movable pulley will raise the height of L relatively, that is, the lifting height of the rope is 2L, that is, s rope = 2 * s rope Draw a picture to compare the distance after the pulley lifting
what you mean by laborious moving the pulley is that the force F acts on the pulley and the weight g acts on the rope, so s force = s moving, s object = s rope. So
F = 2G, s force = 1 / 2S
I hope I can help you!!!!

2. Unknown_Error

3. Difference: if you know the labor-saving distance, it will be laborious to save the distance. If the pulley block is labor-saving in structure (even if the friction and rope weight are ignored), it is not necessarily. If the weight of the movable pulley is quite large, it will be laborious. Because the pulley is just a deformation of the lever.

4. There are three ropes in the moving pulley. One is a fixed rope connected to the pulley. Pulling this rope is laborious. The other two are movable ropes around the pulley. Pulling these two ropes is labor-saving.

the principle of labor-saving of pulley block is to rece the force by extending the action distance, because the work remains unchanged

5. Two kinds of moving pulley
labor saving moving pulley g = 2f-g

laborious moving pulley g = f-2g

F is the tension on the rope; Of course, this is only a single movable pulley, not including the pulley block

6. In fact, it can be
reverse operation of movable pulley
work = force × Distance
labor saving will increase the distance, and the work will not change
labor saving will rece the distance, and the work will not change

7. This is laborious; Save half the distance< If the gravity of the moving pulley is not taken into account, there are two kinds of moving pulley: one is that the dynamic force acts on the wheel, and the other is that the resistance acts on the shaft, which saves half the force and doubles the distance
the other is your situation, where the power acts on the axle and the resistance acts on the wheel. It takes twice the force and saves half the distance;

8. When using the movable pulley, the movable pulley can actually be regarded as the deformation of the lever, and the side of the pulley in contact with the rope is the fulcrum. In this way, in normal use, the power arm is the diameter of the pulley, and the resistance arm is the radius of the pulley. Of course, it will save labor
when used upside down, the original power arm becomes a resistance arm, and the original resistance arm becomes a power arm. At this time, the power arm is only half of the resistance arm. According to the lever balance condition, of course, the power used must be twice of the resistance, so it's hard.

9.

1. Excluding friction:

① gdynamic = fn-g (F is the tension, n is the number of rope segments on the moving pulley, commonly used)

② gdynamic = w / S (W is the additional work done by the machine, s is the moving distance of the moving pulley, rarely used)

③ η= G / (G + G) η For mechanical efficiency, it is more commonly used)

2, when calculating friction,

gdynamic = (wtotal-wye-wf) / S = (wtotal-wf) / S (wtotal work, wye work, WF work to overcome friction)

1, f = g / 2 (idealized, without considering the weight of pulley and only one movable pulley)

2, f = (G + G movable pulley) / 2 (considering the weight of movable pulley and only one movable pulley)

3 F = (G + G movable pulley) / N (n represents the number of rope segments connected to the movable pulley, which is a pulley block)

extended data:

movable pulley can be regarded as a labor-saving lever, O is the fulcrum of the lever, and the axis of the pulley is the action point of resistance. The force of the lifted object on the shaft is resistance, and the force of the rope on the wheel is power

when lifting heavy objects, if the ropes on both sides are parallel, the power arm is twice of the resistance arm; When the moving pulley is balanced, the power is half of the resistance. Therefore, if the gravity of the movable pulley is ignored, half of the force can be saved by using the movable pulley, but the direction of the force can not be changed at this time, and the heavy object can only be lifted by pulling the rope upward

10. When the weight of the pulley is greater than or equal to the weight of the object