"Two Force Balance" Motion and Force PPT Courseware 8

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"Two Force Balance" Motion and Force PPT Courseware 8

One and two force balance

Observe and think

What condition are the skydivers and the chandelier in? What forces act on them?

When an object is at rest or moving in a straight line at a constant speed under the action of several forces, we say that the object is in equilibrium.

When an object is in equilibrium under the action of two forces, we say that the two forces balance each other, or two-force equilibrium for short.

2. Conditions for balance of two forces

Conditions for two force balance:

Two forces acting on the same object balance each other if they are equal in magnitude, opposite in direction, and in the same straight line.

3. Application of two force balance conditions

A. Determine the stress situation according to the motion status

1. The electric lamp suspended at rest is G=20N, and the tensile force of the wire is F=?

2. The teacup resting on the table, m=0.25kg, the support force of the table is N=?

3. For a trailer moving at a constant speed, F pull = 1.5×105N, f resistance =?

B. Judgment of motion status based on force conditions

1. A car is subjected to a pulling force of 50N and a resistance of 30N. How does the car move?

2. A book G=3N, the desktop’s support for it is N=3N, what is the state of the book?

Exchange and discussion

1. When a car is traveling at a constant speed on a straight road, how many pairs of balancing forces are exerted on the trailer behind it? Which of these forces is balanced by gravity?

2. During the tug-of-war between A and B, the pulling force exerted by A on B is F1, and the pulling force exerted by B on A is F2. It is known that F1=F2, then, are these two forces balanced forces? Why?

3. Why is it that when an object is hung under a spring dynamometer and is at rest, the indication of the spring dynamometer is equal to the gravity exerted by the object?

practice

1. Which of the following four figures reflect the balance of two forces ( )

2. The wooden block placed on a horizontal table is at rest. Which of the following pairs of forces is a balanced force ( )

A. The gravity of the wooden block and the pressure of the wooden block on the tabletop

B. The pressure of the wooden block on the tabletop and the support of the tabletop on the wooden block

C. The gravity of the wooden block and the support force of the tabletop on the wooden block

D. The gravity of the wood block and the attraction of the wood block to the earth

3. Among the following objects, which one is acted upon by a balancing force ( )

A. A rocket rising from the ground

B. Stones thrown vertically upward

C. A small ball rolling faster and faster along a smooth slope

D. A car traveling at a constant speed on a straight horizontal road

summary:

1. When an object is acted upon by several forces, if it remains stationary or moving in a straight line at a uniform speed, we say that these forces balance each other and the object is in equilibrium.

(1) The equilibrium state refers to the state of rest and the state of uniform linear motion

(2) The force exerted on an object when it is in equilibrium is the balancing force

2. Conditions for balance of two forces:

Two forces acting on the same object balance each other if they are equal in magnitude, opposite in direction, and in the same straight line.

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For more information about the PPT courseware "Motion and Forces and Balance of Two Forces", please click on the "Movement and Forces ppt Two Forces Balance ppt" tab.

"Conditions for Balance of Two Forces" PPT courseware:

"Conditions for Balance of Two Forces" PPT courseware Part 1: Observation How many forces act on the chandelier? How is your exercise status? The chandelier is acted upon by two forces. The chandelier is stationary. How many forces are exerted on the cargo? How is your exercise status? The cargo is subject to two forces...

"Conditions for Balance of Two Forces" PPT:

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"Two Force Balance" Force and Motion PPT Courseware 2:

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Update Time: 2024-11-20

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

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