What Is a Stalagmometer?

Also known as "elastic force". After an object is deformed by an external force, if the external force is removed, the force that the object can restore to its original shape is called "elastic force". Its direction is opposite to the direction of the external force that causes the object to deform. Because the deformation of an object is various, the elastic force produced also has various forms. For example, when a heavy object is placed on a plastic plate, the bent plastic must return to its original state and produce an upward elastic force. This is its support for the heavy object. Hanging an object on a spring, the object stretches the spring, and the stretched spring must return to its original shape, producing an upward elastic force, which is its pulling force on the object. Not only plastics, springs, etc. can be deformed, any object can be deformed, and objects that do not deform do not exist. However, some deformations are relatively obvious and can be seen directly; some deformations are quite small and must be detected by instruments.

Chinese name: elastic force
Foreign name: elastic force
expression: FN = KX

Applied discipline: physics
Symbol: F
Unit: N (Newton)

Basic elastic information

Elastic word information

[Name]: Elasticity

Pinyin: tán lì

[English]: elastic force ^[1]

Basic explanation of elasticity

elasticity

(1) [elastic force; resilence]: the force caused by the deformation of the elastic body

(2) [life]: the bouncing or elasticity of a substance

Elasticity of the bow

(3) [stretch]: the ability to stretch; flexibility

No loss of elasticity or viscosity

Stretch nylon

Stretch socks

(4) [spring]: The power of spring

Elastic force explained in detail

(1). The force of ejection.

Tang Duancheng's "Yiyang Miscellaneous Paradox": "Zhang Fen once marched for Wei Nankang, performed well in art, held a seven-foot stele, and set a double-wheeled water puppet; he often cuddled at the Fugan Temple, high and half a tower, Five-stretch. "

(2). The power of bouncing.

Lao She's "Camel Xiangzi" 22: "After a run, he felt a lot lighter, and his legs had that kind of elasticity, and he wanted to run again."

(3). The force that causes the object to return to its original shape when the object is deformed.

Hu Yepin's "Go to Moscow": "Everyone sits and lies comfortably on a stretchy Indian satin sofa embroidered with gold threads."

Elastic Oil Painting Name

"Stretch" oil painting

The famous Italian oil painting, by Umberto Boccioni, was created in 1912 and is now in the Museum of Contemporary Art in Milan. It is a futuristic painting.

The meaning of elasticity

Elastic elasticity definition

The change in shape or volume of an object under the action of a force is called deformation. After the external force stops acting, the deformation that can return to its original state is called elastic deformation . The deformed object needs to exert a force on the object in contact with it due to its original state. This effect is called elasticity . That is, within the elastic limit range, the force generated by the object on the urging force that deforms the object is called elastic force.

The interactions observed in daily life, whether it is pushing, pulling, lifting, lifting, or towing a train, forging a workpiece, hitting a ball, arching a bow, etc., occur only when the object is in contact with it Interactions can be called contact forces. Contact force can be summarized into elastic force and friction force according to their properties, which are essentially caused by electromagnetic force.

Elastic force is the contact force. Elastic force can only exist at the place where the objects are in contact with each other, but there is not necessarily an elastic force between the objects in contact with each other. Because the elastic force must not only touch but also interact.

Elastic force is generated between objects that are elastically deformed by direct contact. Generally speaking, pressure, support and tension are all elastic forces. The direction of the elastic force is always opposite to the direction of deformation of the object. The direction of pressure or support is always perpendicular to the support surface and points to the object being pressed or supported.

The so-called pulling force is also elastic. The pulling force of the rope is the elastic force of the rope on the object being pulled, and the direction always follows the rope and points to the direction in which the rope contracts.

When a spring undergoes elastic deformation, within the elastic limit, the amount of elastic force is proportional to the length of the spring (or shortened) (or the extension of the spring is proportional to the tensile force), that is, F = -kx ( or F = -k x ). Among them, k is called the spring's stiffness coefficient (also known as the sturdy coefficient or elastic coefficient), which is numerically equal to the spring force when the spring is extended (or shortened) per unit length. The unit is Newton per meter and the symbol is N / m. The value of k is related to the nature of its material. The difference between soft and hard springs means that their stiffness coefficients are different. And the stiffness coefficients of different springs are generally different. The negative sign in the above expression indicates that the spring force produced by the spring is opposite to the direction in which it expands (or compresses). This law was discovered by the British scientist Hooker and is called Hooker's law . ^[2]

Elasticity conditions

1. Two objects are in contact with each other

2. Elastic deformation of the object (including small deformations that cannot be observed by the human eye)

It should be noted that as long as any object undergoes elastic deformation, it will definitely produce elastic force on the object in contact with it. Once the elastic deformation range is exceeded, the elastic force will be completely lost. Such deformation that exceeds its elastic tolerance range is called "normal deformation". (That is, the elastic limit is exceeded, except for plastic objects)

Example: Wooden block A leans on the wall. If a thrust is applied to wooden block A, the wooden block squeezes the wall and deforms. At this time, there is elastic force between A and the wall. ^[2]

Direction of elasticity

The direction of the elastic force is opposite to the direction of deformation of the object. The specific situations are as follows.

The elastic direction of the light rope is directed along the rope toward the direction in which the rope contracts.

The direction of pressure and supporting force is always perpendicular to the contact surface. The surface-to-surface contact and the point-to-surface contact are all perpendicular to the surface. The point-to-point contact is to find the common cut surface of the two contact points. Point to the support.

The two-force lever (that is, only the two ends of the lever are stressed, and the middle is not subject to force (including the gravity of the lever itself, which is also ignored). It is called the second-force lever. In general, the force of the member is more complicated, and it should be analyzed according to specific conditions.

Rod: The direction of the elastic force is arbitrary, which is determined by the external force and the state of movement.

The relationship between the amount of elasticity and the amount of deformation. Within the elastic limit, the greater the deformation, the greater the elastic force; the deformation disappears, and the elastic force disappears with it. For tensile deformation (or compression deformation), the greater the length of elongation (or shortening), the greater the elastic force generated. For bending deformation , the more severe the bending, the greater the elastic force generated. For torsional deformation , the stronger the twist, the greater the elastic force produced. ^[2]

The nature of elasticity

The essence of elastic force is the intermolecular force. When an object is stretched or compressed, the distance between the molecules will change, making the relative position between the molecules open or close. In this way, the gravitational and repulsive forces between the molecules will not be balanced, and there will be a tendency to attract or repel The overall effect of these molecules' attraction or repulsion is the elasticity observed macroscopically. If the external force is too large, the distance between the molecules is pulled too far, and the molecule will slide into another stable position. Even after the external force is removed, it cannot return to the restoring position, and the permanent deformation will remain. This is the essence of elasticity. ^[2]

The difference between elasticity and elasticity

Elasticity is named after the nature of the force. The pressure, support, and tension are named by the effect of the force. These are two completely different concepts. Therefore, there is no clear relationship between elasticity and pressure, support, and tension. Elastic force is not necessarily pressure, support, and pull.

For example, two ring magnets sleeved on the same smooth vertical rod have the same magnetic poles facing each other, and both magnets are at rest. The force analysis of the upper magnet is performed. The magnet is subjected to its vertical downward gravity and vertical upward repulsive force. The two forces are a pair of balanced forces. At this time, the upward repulsive force serves as a supporting force. This support is not elastic. In addition, according to Newton's third law, the magnitude is equal to the upward repulsive force, and the downward magnetic force also acts on the underlying magnet. At this time, the downward magnetic force is the downward pressure given by the magnet above. This pressure is not elastic.

For another example, between two smooth parallel straight guide rails, a uniform magnetic field with a vertical direction and an equal distance distribution direction is distributed, and a metal frame with the same width as the magnetic field is arranged on the guide rails. When the magnetic field moves at a constant speed, the wire frame is moved by the ampere force. At this time, the ampere force is the combined external force of the wire frame movement, that is, the pulling force. This tension is not elastic.

Therefore, we cannot say in general that elasticity is pressure, support, and pull. To analyze the specific situation. It depends on the meaning of the title. ^[2]

Elastic deformation

The object will deform after being stressed. If the object can return to its original state after the force is removed, this deformation is called elastic deformation.

Elastic plastic deformation

The external position of the object changes the relative position between the points. When the external force is withdrawn, the object cannot return to its original state, which is called "plastic deformation" ^[2]

When an external force is applied to a large enough body, a permanent shape change will occur, that is, the shape change can be preserved after the external force is removed. This property is called paradigm. Now more often it is called plasticity.

Plasticity is a material property that a material undergoes permanent deformation under a given load. For most engineering materials, when the stress is below the proportional limit, the stress-strain relationship is linear. In addition, most materials exhibit elastic behavior when their stress is below the yield point, that is, when the load is removed, their strains completely disappear. Plasticity can be expressed by elongation and sectional shrinkage .