"How to describe motion" Motion and force PPT courseware

"How to describe motion" Motion and force PPT courseware

teaching objectives

1. Know what mechanical motion is

2. Know that to judge whether an object is moving, you must first select a reference object, and be able to scientifically describe the movement and rest of the object based on the reference object.

3. Understand that there are various forms of movement in nature

4. Know the relativity between motion and stillness

1. Mechanical movement

In physics, the change of the position of one object relative to another is called mechanical motion (referred to as motion).

2. Reference objects

When judging whether an object is moving, another object selected as a reference is called a reference object.

Thinking: If the ground is used as a reference, then: the green mountains in the picture are _____, the white clouds staying on the top of the mountains are also _____; the waterfalls are _____.

In this picture, are the people in the sightseeing elevator stationary or moving?

Using the ground as a reference, people are in motion;

Taking the elevator as a reference object, people are stationary.

3. Relativity of movement

Whether the same object is moving or stationary depends on the chosen reference object. Depending on the reference object, it may be said that the object is moving or it may be said that the object is stationary. This property of mechanical motion is called the relativity of motion.

Summary: Five levels of meaning need to be explained about reference objects:

1. To describe the motion of an object, you must first select a reference object. A reference object is an object that is assumed to be immobile.

2. The reference object is the object selected as a reference when studying mechanical motion. It does not mean that the object is stationary.

3. The reference object can be selected arbitrarily. But you cannot select the object itself as a reference

4. For the same object, the motion state can be different if the reference object is different.

5. Generally, the ground or an object stationary relative to the ground is selected as the reference object.

Class summary:

1. In physics, the change of the position of one object relative to another object is called mechanical motion (referred to as motion).

2. When judging whether an object is moving, another object selected as a reference is called a reference object.

3. Whether the same object is moving or stationary depends on the selected reference object. Depending on the reference object, it may be said that the object is moving or it may be said that the object is stationary. This property of mechanical motion is called the relativity of motion.

4. The reference object can be selected arbitrarily, but it should be determined according to needs and convenience. When studying objects on the ground, the ground is often chosen as a reference object.

Class exercises:

1. The _______ of one object relative to another object is called mechanical motion.

2. Using the ground as a reference, the trees on the roadside are ____; if you sit on a moving school bus and watch the trees on the roadside recede, you are using ____ as a reference.

3. We usually think that teaching buildings are stationary, but in fact we use ____ as the reference object; if the sun is used as the reference object, the earth is ____, and the teaching buildings on the earth are also ____.

Operation:

Classwork: Page 2, 3, and 4 on P41

Tutorial (preview):

1. Two ways to compare the speed of an object’s movement

2. Speed ​​and its calculation formula

3. What is uniform linear motion? What is variable speed linear motion

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"How to describe motion" Motion and force PPT courseware 2:

"How to describe motion" Motion and force PPT courseware 2 1. What is motion and rest 1. Mechanical motion When students ride bicycles, the positions of the man and the bicycle relative to the ground are constantly changing; when a train is running on the rails, its position relative to the ground The position is constantly changing; flying...