"Newton's First Law" Motion and Force PPT Courseware 2

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"Newton's First Law" Motion and Force PPT Courseware 2

Class memories:

What is the effect of force?

1. Force can change the shape of an object;

2. Force can change the motion state of an object.

What does exercise status mean?

From rest to motion; from motion to rest; change of direction of motion; change of speed of motion.

What does it mean that the motion state remains unchanged?

Objects always remain at rest or move in a straight line at a constant speed.

Knowledge point 1: The influence of resistance on the movement of objects

Observe and think about the following phenomena?

1. Apply a horizontal thrust to the stationary wooden box, and the wooden box moves in the horizontal direction. After the thrust was removed, the wooden box stopped.

2. Although the train with the engine turned off continues to run, it will eventually stop.

Experimental conclusion: The smoother the horizontal surface, the smaller the resistance the car receives and the greater the distance it moves. In other words, the smaller the resistance the car receives, the slower the speed decreases.

Further reasoning from the above experiment leads to the conclusion that if the surface is absolutely smooth, the resistance encountered by the object is 0 and it will continue to move at a constant speed forever. This experiment can conclude that Galileo's statement is correct.

The motion of an object does not require force to maintain it. Aristotle believed that the force that needs to be added is actually used to balance the resistance.

Exercises to practice pen writing

1. Regarding Galileo’s ideal experiment, which of the following statements is correct ( )

A. Totally ideal and not based on facts

B. It is based on reliable facts and profoundly reflects the laws of nature through scientific abstraction.

C. Not based on facts, just ideal reasoning

D. None of the above statements are correct

2. Galileo’s inclined plane experiment proved ( )

A. For an object to move, there must be a force acting on it. Without the force acting on it, an object will remain at rest.

B. For an object to be at rest, a force must be exerted; without force, an object will move.

C. An object must be at rest when no external force acts on it

D. When an object is not acted upon by an external force, it always maintains its original state of uniform linear motion or rest.

3. The scientist who first came to the correct conclusion that "the speed of all objects remains unchanged when there is no external force" is ( )

A. Archimedes

B. Descartes

C. Galileo

D. Newton

All objects always maintain a state of uniform linear motion or a state of rest when they are not acted upon by external forces.

1. “Everything” applies to all objects;

2. “No external force” is the condition for the law to be established

3. "Always maintained" means that when an object is not acted upon by an external force, it has only two possibilities: stationary or uniform linear motion.

4. "Or" means that one of the two states must exist, not at the same time.

Newton's first law was not derived directly through experiments, but was summarized by reasoning based on a large number of experiments. It cannot be directly proven by experiments.

[Example 1] A small ball is tied with a rope and moves in a circular motion on a smooth horizontal surface. When the rope suddenly breaks, the small ball will [ ]

A. Maintain the original circular motion.

B. Keep the speed at which the rope was broken and move in a straight line at a constant speed.

C. The speed of the ball decreases but remains straight.

D. All three of the above are possible.

[Analysis] It turns out that the ball is moving in a circle due to the tension of the rope. When the rope suddenly breaks, the ball no longer receives force in the smooth horizontal direction, so the ball will keep the speed and direction at the moment when the rope breaks.

inertia

1. Definition: The property that keeps an object at rest or moving in a straight line at a uniform speed is called inertia.

2. Three points of understanding of inertia

(1) Inertia is a property of the object itself.

All objects have inertia, regardless of external conditions. It has nothing to do with the state of the object, whether the object is moving or stationary, whether the object is subject to force, the magnitude of the speed, and other external conditions.

(2)Inertia is not a force.

Force is the effect of an object on an object, while inertia is an inherent property of the object itself. Inertia only has size but no direction.

(3) The inertia of an object is only related to the mass of the object.

All objects have inertia, but the inertia of different objects is different. The greater the mass of the object, the greater the inertia; the smaller the mass of the object, the smaller the inertia.

summary

1. The content of Newton’s first law: All objects always remain at rest or move in a straight line at a uniform speed when not acted upon by external forces.

2. Inertia: The property of an object to maintain a state of motion is called inertia.

All objects have inertia under any circumstances, and inertia is an inherent property of the object.

All objects under any circumstances: whether they are subject to force, whether they are moving, how fast they are moving, and whether they are moving at a uniform speed.

3. Inertia phenomenon and explanation

The difference between inertia and Newton's first law of motion.

1. Inertia: the property of an object. Without any conditions, all objects have inertia.

2. Newton's first law: the law of motion of an object without force.

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For more information about the "Newton's First Law of Motion and Forces" PPT courseware, please click the PPT tag of "Motion and Forces PPT Newton's First Law".

"Newton's First Law" Motion and Force PPT (Lesson 2):

"Newton's First Law" Motion and Force PPT (Lesson 2) Part One: Classification Practice of Knowledge Points Knowledge Point 1 Inertia 1. Regarding the inertia of an object, which of the following statements is correct ( ) A. Inertia is a property of an object B. An object only has inertia when it is at rest.

"Newton's First Law" Motion and Force PPT (Lesson 1):

"Newton's First Law" Motion and Force PPT (Lesson 1) Part 1: Classification practice of knowledge points Knowledge point 1 The influence of resistance on the movement of objects 1. The football rolling on the ground rolls slower and slower, and finally stops because the football is affected by the _____ on the ground.

"Newton's First Law" PPT download of motion and force:

"Newton's First Law" PPT Download of Motion and Force Part 1 Content: Preview Perception 1. The Effect of Resistance on the Movement of Objects 1. The smoother the horizontal surface, the smaller the resistance the car will experience. The slower the car's speed will decrease, the slower the car will move. The longer. 2. If the car transports...

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Update Time: 2024-11-22

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

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