Considering that rhinitis is easy to aggravate when catching a cold or getting angry, strenuous activities should be avoided at ordinary times.
Guiding opinions:
Consider or take the initiative to massage hot compress, light diet or suggestion? Take care of yourself, but you'd better avoid catching a cold and pay attention to rest and hygiene.
mechanical movement
In physics, the position change of one object relative to another object is called mechanical motion, which is referred to as motion for short. Mechanical motion refers to the change of the position of an object relative to other objects, which is the simplest and most basic form of motion in nature.
Relativity between motion and stillness
Everything in nature is in motion, because the earth itself is rotating, so absolutely stationary objects do not exist. Usually, the motion or static of the described object is relative to a reference object. Whether the same object is moving or static depends on the selected reference object, which is the relativity of motion and static.
Relative static state: two objects move in the same direction at the same speed.
form
There are various forms of mechanical movement, some moving along a straight line and some moving along a curve; Some are moving on the same plane, others are not. Some people walk fast, others walk slowly. .......................................................................................................................................................................
Exercise:
Motion is a universal phenomenon in the universe. Broadly speaking, all objects in the universe are moving, and there is no absolutely static object; Motion in a narrow sense refers to mechanical motion.
Still:
An object is said to be at rest when its position relative to another object has not changed. Static is relative to motion, and there is no absolutely static object.
Mechanical movement:
Mechanical motion: In physics, the change of the position of an object (the change of the position of one object relative to another) is called mechanical motion. It is usually referred to as exercise for short.
Method of judging mechanical motion:
Mechanical motion is a common phenomenon in the universe. Everything is in motion, and absolutely still objects do not exist. The basis for judging whether an object does mechanical motion is to see whether the position of this object relative to another object has changed. If there is, we say that this object is moving mechanically relative to another object.
Linear uniform motion
Definition: uniform linear motion? When an object moves in a straight line, if it travels the same distance at any one time, this motion is called uniform straight line motion.
Uniform linear motion is the simplest mechanical motion and the basis for studying other complex motions. Objects moving in a straight line at a uniform speed have the same distance at any one time, that is, the distance is proportional to time; Speed does not change with distance and time; Displacement equals distance.
(1) Distance: The length of the path traveled by a moving object is called distance. In the international unit, the unit of distance is meter.
(2) Three methods to compare the speed of objects.
1. Compared with the time required for an object to travel the same distance, an object with a short time moves faster.
2. Compare the distance an object has traveled in the same time. The longer the distance, the faster the object moves.
3. When the distance and time traveled by an object are not equal, compare the ratio of distance to time (the distance traveled per unit time), and the one with the larger ratio moves faster [1]?
(3) Physical meaning, definition and formula of speed.
1. Physical meaning: Speed is a physical quantity indicating the speed of an object.
2. Definition: The displacement of an object moving in a straight line at a uniform speed per unit time is called the speed of the object.
3. calculation formula: V=S/T
4. International unit: meters per second (m/s); Commonly used unit: km/h; 1 m/s =3.6 km/h
5. Independent of displacement (x) and time (t).
6. Speed is a vector with direction and magnitude. Be careful not to forget to describe the direction of speed when describing.
Variable speed linear motion
1. Variable speed linear motion: the object moves in a straight line. If the distances traveled at the same time are not equal, this movement is called variable-speed linear movement.
2. Average speed
1. Definition: The average speed of an object during this time is the distance traveled by the object in a variable-speed linear motion divided by the time spent.
The average speed can only roughly describe the speed of a variable-speed linear moving object. When calculating the average speed, be sure to specify which time period or distance it is.
2. calculation formula: V=S/T
3. International unit: meter per second (m/s) or m.s- 1 power.
Junior high school version definition
brief introduction
Mechanical motion is the most common phenomenon in the universe. Motion is relative, and stillness is relative.
The change of relative position between objects or parts of the same object with time is called mechanical motion. This is the simplest and most common form of material movement. For example, the rotation of the earth, the tension and compression of springs are all mechanical movements. Other complex forms of motion, such as thermal motion, chemical motion, electromagnetic motion and life phenomena, all contain position changes, but they cannot be simply attributed to mechanical motion.
All objects are in motion, and there is no absolutely stationary object, which means that motion is absolute. We usually say that motion and stillness are relative to another object, so the description of stillness is relative.
reference substance
1) To describe the position change of one object, another object must be selected as the standard. Another object chosen as a standard is called a reference object.
2) Choose different reference frames to observe the movement of the same object, and the observation results may be different. For example, people who live on the earth think that the earth is stationary, but in fact the earth revolves around the sun at a huge speed of 30 km/s, which is the relativity of physical movement and stillness.
3) The choice of reference is arbitrary, and the result of description will be different.
classify
According to the route of motion, objects can be divided into linear motion and curved motion. [2]?
Generally speaking, linear motion is simpler than curvilinear motion. But the linear motion is also very different, so it is necessary to classify the linear motion.
Linear motion can be divided into uniform linear motion and variable linear motion according to its speed variation characteristics:
1) Uniform linear motion is called uniform linear motion;
2) The object moves in a straight line. If the distances traveled at the same time are not equal, this movement is called variable-speed linear movement.