Fixed pulley problem, movable pulley and fixed pulley

OK. Go a little further so that the rope is pulling you diagonally.

You are affected by the ground horizontal friction, gravity, and rope tension three forces, gravity 160, tension 161, to balance the three forces, as long as the ground friction is greater than (pull square - gravity square) and then open the square = on it, it is normal for the friction coefficient between the ground and you to be greater than this condition.

Therefore it is achievable.

OK. If your feet are fixed to the ground. Otherwise, it will be pulled up by the box.

No, the force on both sides of the fixed pulley is equal, and you can only balance with the 160-pound box, and you can't pull the 161-pound box.

No, even if you have infinite arm strength, if your feet are not fixed, you can use a large rope at most to exert a pull equivalent to your body weight, because the force is reciprocal, and the rope also has a strong effect on you, beyond which you will get off the ground and climb up the rope. And at this time, the amount of tension on the rope is equal to the amount of your gravity is not enough to pull up the object.

No way. The force of each rope of the fixed pulley is equal, and the fixed pulley can only change the direction of the force but not the magnitude of the force. If the force on one side is determined, the force on the other side is also determined.

Cable-stayed pull can. The reasonableness of the friction and its own gravity can be pulled up by the box.

Fixed pulley: fixed in one place, can not move with the movement of heavy objects.

Movable pulley: not fixed, can move with the movement of heavy objects.

Features: 1. Fixed pulley.

The fixed pulley is a kind of fixed pulley, its fixation is not simply fixed, but the central axis of the pulley is fixed, the main advantage of the fixed pulley is that it can change the direction of the force, when we use the fixed pulley to pull a very heavy object, it is not very hard.

2. a movable pulley.

The use of movable pulley can save half of the force, the distance, this is because when using the movable pulley, the hook code is hung by two sections of rope, each section of the rope only bears half of the weight of the hook code, although the use of the movable pulley saves force, but the distance of the power movement is 2 times the distance of the hook code elevated, that is, the distance.

See the diagram below: <>

Labor-saving calculations. Formula: s = nh, v rope = n * v matter f pull = (1 n) * g total.

s: The distance traveled by the free end of the rope. V-rope: The speed at which the free end of the rope moves (ascends, descends).

h: The height at which the weight is lifted. v-object: The speed at which an object moves (rises, falls).

n: The number of load-bearing rope segments (rope connected to the movable pulley). G total: weight + pulley weight (G object + G slip).

Secondly, determine the number of fixed pulleys according to the requirements, and the principle is: general: two strands of rope with a movable pulley.

The fixed pulley is essentially an equal arm lever, and the power arm L1 and the resistance arm L2 are equal to the radius of the pulley.

First, the fixed pulley information

1. The central axis of the fixed pulley is fixed. The function of the fixed pulley is to change the direction of the force, but it cannot save the force. When pulling heavy loads, a fixed pulley can be used to change the direction of force application to the direction of easy force output.

2. When using the fixed pulley, the distance of force pulling is equal to the distance of the object rising, which cannot be labor-saving or labor-intensive. The tensile force at both ends of the rope is equal, so the mechanical efficiency of the fixed pulley is close to 1 when the output force is equal to the input force, excluding friction.

2. Advantages and disadvantages.

1. Fixed pulley, which is physically defined as a pulley with a fixed position of the shaft. Although the fixed pulley can not save force when it is used, it can change the direction of our force, and it also costs distance. The fixed pulley is a kind of fixed pulley, and its fixation is not simply fixed, but the central axis of the pulley is fixed.

2. The main advantage of the fixed pulley is that it can change the direction of the force, when we use the fixed pulley to pull a very heavy object, it is not very hard, but we can change the direction of the force through a fixed pulley to the direction of our good force, so that it is easy to pull the heavy object.

3. The disadvantage of the fixed pulley is that it cannot save effort. In other words, the force we use with the fixed pulley is the same as the force we use without the fixed pulley. But we can overcome its shortcomings with a simple pulley set.

1. The essence of the fixed slide is an equal arm lever, which is not labor-saving or labor-intensive, but can change the direction of force. The power arm and resistance arm of the lever are respectively the radius of the pulley, and since the radius is equal, the power arm is equal to the resistance arm, and the lever is neither labor-saving nor labor-intensive.

2. The fixed pulley can not be blocked and labor-saving, and in the case of the rope weight and the friction between the rope and the wheel are not counted, the force used to lift the heavy object is equal no matter where the force direction of the rope goes, because the power arm and the resistance arm are equal and equal to the radius of the pulley.

3. The movable pulley saves 1 2 force and costs 1 times more distance, because when using the movable pulley, the hook code is suspended by two sections of rope, and each section of the rope only bears one and a half of the weight of the hook code, and can not change the direction of the force. In essence, it is a lever that is twice the power arm (L1) and the resistance arm (L2).

The essence of the fixed pulley is the difference between the bright and the laughing equal arm lever. Fixed pulley refers to the position of the shaft fixed pulley, it is not labor-saving and effortless, the main role is to change the method of force, when pulling heavy objects, with the fixed pulley can change the direction of force, into the direction of easy force. The power arm of the fixed pulley is equal to the resistance arm and equal to the radius of the pulley.

The fixed pulley is actually not labor-saving and labor-saving, its main pass is the method of changing the force, the power arm and the resistance arm of the fixed pulley lever are the radius of the pulley, because their radius is imaginary equal, so the power arm is equal to the resistance arm, and the lever composed in this way is neither laborious nor labor-saving.

That is to say, can not utilize the fixed pulley to achieve the purpose of saving labor, in the case that the friction between the rope weight and the rope and the wheel is not counted, the force direction of the rope is no matter where it is, the force used to lift the heavy object is equal, so the power arm and the resistance arm are equal, and are equal to the radius of the pulley.

What is a fixed pulley

When using a pulley, a pulley with a fixed shaft position is called a fixed pulley, and according to the lever theorem, it is essentially an equal-arm lever. In the case of one-key digging, when pulling heavy objects, a fixed pulley can also be used, so that the direction of force can be changed to the direction of easy force.

Vertical pulley group: The number of rope segments on the movable pulley is n

The tension force at the free end of the rope is f, the gravity of the object is g, the moving pulley weight g1 moves the distance of the free end of the rope s, and the object moves away h

The free end of the rope moves at a speed v, and the object moves at a speed v1

Then: the relationship of force:

f=gTotal n

If it is an ideal situation, ignore the gravity of the moving pulley, the weight of the rope, the friction force, etc.: f=g n If it is a real situation, consider the gravity of the moving pulley: f=(g+g1) n distance relationship:

s=nh (both practical and ideal) velocity relation: v=nv1 (both practical and ideal) mechanical efficiency. =W has w total=GH fs=g nf=w has w total=w has (w has +w extra)=g (pure tung g + g moving) horizontal sliding stove lead wheel:

The number of rope segments on the movable pulley is good n for hidden pants

The tension force at the free end of the rope is f, and the object resistance is f

The distance traveled at the free end of the rope is s, and the distance traveled by the object is s1

The free end of the rope moves at a speed v, and the object moves at a speed v1

Then: the relationship of force:

f=f n distance relation: s=ns1

Velocity relation: v=nv1