"Measurement of Elasticity and Force" Motion and Force PPT Courseware

Description

"Measurement of Elasticity and Force" Motion and Force PPT Courseware

Knowledge review

Force: The effect of one object on another object, represented by the letter F

Unit of force: Newton ( )

The effects of forces between objects are mutual

force effect

1. Force can change the motion state of an object

2. Force can deform objects

Three elements of power:

big small

direction

point of action

Representation of force:

Illustration of force

force diagram

1. Elasticity

Pull the spring, rubber band and squeeze the plasticine and dough with force respectively; after letting go, what is the difference in the result?

flexibility and flexibility

The property of an object that deforms under the action of a force and can return to its original shape after the external force is removed is called elasticity.

The characteristic that an object cannot automatically return to its original shape after deformation is called plasticity (plasticity).

The change in the shape of an object is called deformation.

Elastic deformation: deformation that can return to its original shape after the external force is removed

Parametric deformation: a deformation that cannot return to its original shape after the external force is removed.

cause:

An object that undergoes elastic deformation will exert a force on the object in contact with it because it wants to return to its original shape. This force is called elastic force.

(Contact each other and elastically deform.)

Size: The size of the elastic force is related to the size of the elastic deformation.

(Within the elastic limit, the greater the deformation, the greater the elasticity; when the deformation disappears, the elasticity disappears.)

Direction: Opposite to the direction of elastic deformation of the object.

Types of elasticity: push, pull, lift, pressure, support.

Summary of the direction of elasticity

The direction of pressure and support forces is always perpendicular to the contact surface and toward the object being pressed or supported.

The direction of the pulling force of the suspension line on the object is always along the suspension line and points in the direction of the contraction of the suspension line.

2. Measurement of force - dynamometer

Principle: The spring deforms when it is subjected to pressure or tension. Within a certain range, the greater the tension or pressure, the greater the deformation of the spring.

Use of spring dynamometer

before use:

Use the first three to look at:

First look at the measuring range: observe the measuring range and choose a dynamometer with the appropriate measuring range.

2. Check whether the pointer is pointing at zero mark

Third, look at the minimum graduation value to determine the accuracy of the spring dynamometer.

when using it:

Check later: Before measuring, gently pull it back and forth several times with your hands to avoid friction between the pointer, spring and housing, which may affect the accuracy of the measurement.

Second meeting: when measuring, apply force along the central axis of the spring

Three meetings: The line of sight should be perpendicular to the scale surface, and the dynamometer should be kept at rest or in a state of uniform linear motion.

Four-level reading: No need to estimate the reading, the value of whichever scale line the pointer is close to will be read.

Note: When measuring upside down, the measured value will be larger.

summary:

1 elasticity

1. Elastic deformation and normative deformation

2. Elastic force: The force exerted by an object on the object in contact with it due to its elastic deformation and its return to its original shape.

2. Spring dynamometer

1. Purpose: Measuring the size of force

2. Principle: The greater the force on the spring, the greater the deformation of the spring.

3. Structure: spring, dial, pointer, hook

4.Usage: three times before use, four times after use

Do it

1. Pull the dynamometer with your hand and feel the force of 2N and 5N.

2. Use a spring dynamometer to measure the maximum pulling force a hair can withstand.

think about it

Squeeze the glass bottle with your hands, and the glass bottle will deform slightly.

1. As shown in the figure on the right, the spring dynamometer has a measuring range of ____ and a graduation value of ____. The current indication of the spring dynamometer is ____N.

2. There is a spring dynamometer. When no force is exerted on the scale hook, the pointer is not on the zero scale line, but at the 0.2N position. At this time, the spring dynamometer scale hook is pulled by hand, and the reading is 4N, then The force of the hand pulling the spring is ( )

A. 4.2N B. 4N

C. 3.8N D. Unable to judge

3. During the tug-of-war between the two groups, group A pulled group B over. Which of the following statements is correct ( )

A. The force of group A pulling group B must be greater than the force of group B pulling group A.

After group B gives an action force to group B, group B gives a reaction force to group A.

C. Group A can win only if the force of group A pulling group B is greater than the force of group B pulling group A.

D. The force of group A pulling group B is always equal to the force of group B pulling group A.

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For more information about the "Motion and Force Measurement of Elastic Force" PPT courseware, please click the "Motion and Force ppt Measurement of Elastic Force ppt" tag.

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Update Time: 2024-07-04

This template belongs to Physics courseware Beijing Normal University eighth grade physics volume 2 industry PPT template

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