What are the benefits of an equal arm lever, and what are the advantages and disadvantages of an equ

Change the direction of the force, and the magnitude of the force remains the same.

If the arms are of equal length, then the amount of force on both sides can be directly judged by the rotation.

An equal-arm lever is like a balance that accurately measures the mass of an object.

What are the benefits of equiarm leverage? The ancient Greek scientist Archimedes had such a famous saying that has been passed down through the ages:"If you give me a fulcrum, I can move the earth! "This sentence is not only an inspiring aphorism, but also has a strict scientific basis.

Archimedes was the first to propose the principle of leverage in his book On the Equilibrium of Plane Figures. He began by taking some empirical knowledge of the practical application of leverage"A self-evident axiom"Then, starting from these axioms, using geometry through rigorous logical arguments, the lever principle is derived. These axioms are:

1) Hang equal weights at the ends of the weightless rod at an equal distance from the fulcrum, and they will balance; (2) Hang unequal weights at the two ends of the weightless rod at an equal distance from the fulcrum, and the heavy end will tilt downward; (3) Hang equal weight at the two ends of the weightless rod at an unequal distance from the fulcrum, and the far end will be tilted down; (4) The action of one weight can be replaced by the action of several evenly distributed weights, as long as the position of the center of gravity remains the same. Conversely, several evenly spaced weights can be replaced by one suspended at their center of gravity; The center of gravity of the figure is distributed in a similar way ......It is from these axioms that in"Center of gravity"On the basis of the theory, Archimedes discovered the principle of leverage, namely"When the duo is balanced, their distance from the fulcrum is inversely proportional to their weight. "

Archimedes' study of levers is not only theoretical, but also includes a series of inventions based on this principle. It is said that he once used levers and pulleys to launch a mast boat parked on the beach. During the battle to defend Syracuse from the Roman navy, Archimedes used the principle of levers to create catapults at close and close range, using them to shoot various missiles and boulders to attack the enemy, and once held the Romans out of the ancient city of Syracuse for three years.

It is also worth mentioning here that there have long been records about leverage in the history of our country. The Mohists of the Warring States Period once summarized the laws in this regard, and there are two special records of the principle of leverage in the "Book of Ink". These two articles speak comprehensively about the balance of leverage.

There are those with equal arms, and there are those with unequal arms; There are those who change the weight of the ends to deflect it, and there are those who change the length of the arms to deflect it. Such an account is also very valuable in the history of world physics.

Examples of labor-saving levers: nut clips, doors, staplers, diving boards, wrenches; Laborious levers: tweezers, arms, fishing rods, paddles for kayaks, jaws; Equal-arm levers: seesaws, balances; The specific analysis is as follows:

In junior high school physics, a hard rod that can rotate around a fixed point under the action of force is called a lever;

Classification of leverage:

Category 1: The fulcrum is in the middle of the power point and the resistance point. This is called the first type of leverage. The power arm is the same length as the resistance arm, so this type of lever is an equiarm lever. Examples: seesaw, balance;

Type 2: The resistance point is between the power point and the fulcrum. This is called the second type of leverage. Since the power arm is always larger than the resistance arm, it is a labor-saving lever. Examples: nut clips, doors, staplers, diving boards, wrenches;

Three categories: The power point is between the fulcrum and the resistance point. This is called the third type of leverage. The power arm is shorter than the resistance arm, so this type of lever is a laborious lever, but it saves distance. Examples: tweezers, arms, fishing rods, paddles for kayaks, jaws;

So it can be seen that examples of labor-saving levers, labor-saving levers, and equal-arm levers.

A kind of lever, the power arm and the resistance arm are the same length, there are no specific advantages and disadvantages, the main feature is that it is neither labor-saving nor labor-intensive, neither distance nor distance-saving.

Labor-saving lever: the power arm is larger than the resistance arm, and the power is less than the resistance when balanced, although it saves effort, but it takes a distance.

Laborious dust core lever: The power arm is shorter than the resistance arm, that is, the power is larger than the resistance, which is laborious but saves distance.

1. Labor-saving lever: while saving labor, it costs distance. The driving force (application point) travels a large distance, while the resistance force (application point) travels a small distance.

Such as crowbars, claw hammers, bottle openers, walnut clips, etc.

2. Laborious lever: It cannot save effort, but it can save distance. The driving force (application point) travels a small distance, whereas the resistance force (application point) travels a large distance.

Such as chopsticks, fishing rods, tweezers, food tongs, etc.

3. Equal arm lever: neither effort nor distance can be saved. The distance traveled by the kinetic force (the point of application) is equal to the distance that the resistance (the point of application) moves.

Such as balances, seesaws, etc.

Classification and judgment conditions of leverage:

1. If l1 l2, then f1 f2, this lever is called the arm lever of the Ant Hand Song;

2. If L1 L2, then F1 F2, this lever is called labor-saving lever;

3. If L1 L2, then F1 F2, this lever is called laborious lever.