"Lever" Simple Machinery PPT Courseware

Description

"Lever" Simple Machinery PPT Courseware

1. Lever: A hard rod that can rotate around a fixed point under the action of force is called a lever.

Similarity

powerful effect

rotate around a fixed point

hard rod

1. Meet the conditions for leverage (two):

(1) It must have a powerful effect

(2) Able to rotate around a fixed point

2. Note: The shape of the lever can be straight or curved, but it must be hard and not deformed even when used.

3. Five elements of leverage

Fulcrum O: The point around which the lever rotates

Power F1: the force that causes the lever to rotate

Resistance F2: the force that hinders the rotation of the lever

Power arm l1: the vertical distance from the fulcrum to the power action line

Resistance arm l2: the vertical distance from the fulcrum to the resistance line of action

Note: The moment arm is the distance from the fulcrum to the line of action of the force, not the distance from the fulcrum to the point of action.

2. Explore the equilibrium conditions of leverage

[Activity] Can two people with different weights stabilize the seesaw?

1. The equilibrium state of the lever: stationary or slow and uniform circular rotation.

[Thinking] What conditions must be met for leverage to be in equilibrium?

[Conjecture] If the force is large, the corresponding stress arm will be small, and if the force is small, the corresponding stress arm will be large.

2) There are two adjustable nuts installed at both ends of the lever, which are used to adjust the lever to balance it in a horizontal position.

Adjustment method: Left high, left light, left

Right high, right light, right

Explore the equilibrium conditions of leverage

3) Experimental steps:

1. Adjust the lever to balance in the horizontal position.

2. Hang an appropriate amount of hook code on the left side of the lever, use a spring dynamometer to pull it in the vertical direction to balance the lever in a horizontal position, and record the spring dynamometer indication.

3. Change the number or position of the hook codes and repeat the above steps to get three sets of data.

5. Application of Leverage Principle

1. Calculation of balancing factors

method

1. Build a model reasonably and clarify the balancing elements

2. Correspond to the leverage principle and implement formula deformation

3. Pay attention to the unity of units and standardize the problem-solving process

2. Analysis of dynamic balance

As shown in the figure, the lengths of each square marked on the lever with negligible mass are equal, 0 is the fulcrum, each hook number hung on both sides of the lever is the same, and the lever is balanced in a horizontal position. In the following cases, the lever is still balanced in the horizontal position ( )

A. Reduce one hook code on both sides

B． Add an identical hook code under the hook codes on both sides.

C. The hook code on the left moves one space to the right, and the hook code on the right moves one space to the left at the same time.

D． Add a same hook code on the right, and move the hook code on the left one space to the left at the same time.

Dynamic Balance Analysis

As shown in the figure, a light lever can rotate around the axis O. A weight is hung at the midpoint of the straight bar. A force F is applied to the other end of the bar to slowly lift the straight bar from the lower right position to the horizontal position. In , the change in the magnitude of force F is ( )

A. Keep increasing B. Keep decreasing

C. Remain unchanged D. Unable to determine

As shown in the figure, hang a weight on the midpoint of a light lever, apply a force F on the other end of the lever to keep the lever balanced, and then turn F to the right to the horizontal direction. The change of F during this process is ( )

A. Keep increasing B. Keep decreasing

C. Get smaller first and then get bigger D. Get bigger first and then get smaller

Keywords: Simple Machine Teaching Courseware, Leverage Teaching Courseware, New People's Education Edition Physics PPT Courseware for 8th Grade Volume 2, 8th Grade Physics Slide Courseware Download, Simple Machinery PPT Courseware Download, Leverage PPT Courseware Download, .ppt format

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Update Time: 2024-07-07

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 2 industry PPT template

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