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Compulsory 1 focuses on force, resultant force, component force, parallelogram law of force, three common types of force, three elements of force, time, moment, displacement, distance, speed, rate, instantaneous velocity, average velocity, average velocity, acceleration, and common-point force equilibrium (equilibrium condition).
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Physics is very easy to do. You definitely can.
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Go to the college entrance examination of the post bar, there is everything in it!
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Motion is absolute, and rest is relative. Whether an object is in motion or at rest is relative to the frame of reference.
The choice of frame of reference is arbitrary, and the object chosen as the frame of reference, we assume that it is stationary. Choosing different objects as reference frames may lead to different conclusions, but the description of the movement should be as simple as possible.
The ground is usually used as a frame of reference.
2. Particle point: Definition: A point with mass used to replace an object. A particle is an idealized model, an abstraction of science.
The condition for an object to be considered as a particle: when studying the motion of an object, the size and shape of the object have a negligible influence on the results. And whether the object can be regarded as a particle point should be analyzed on a case-by-case basis.
There are several situations in which an object can be considered a particle:
1) Translational objects can usually be regarded as particles.
2) When there is rotation but it is negligible relative to translation, the object can also be regarded as a particle.
3) The same object can sometimes be seen as a particle, sometimes not. When the size of the object itself has a non-negligible impact on the problem under study, the object cannot be regarded as a particle, and vice versa.
Note (1) The size and shape of the object cannot be used as the criterion to judge whether the object can be regarded as a particle, and the key depends on the nature of the problem under study. When the size and shape of the object have a negligible effect on the problem under study, the object can be considered a particle.
2) A particle is not a point with very little mass, but it is different from a "point" in geometry.
3. Time and time:
A moment is a moment in time, represented by a point on the timeline, which corresponds to the amount of state; Time is the interval between the start moment and the end time, represented by a line segment on the timeline, which corresponds to the amount of process.
4. Displacement and distance:
Displacement is used to describe the change of the position of the particle, which is a directed line segment of the particle from the initial position to the last position, which is a vector;
The distance is the length of the trajectory of the particle and is a scalar quantity.
5. Velocity: The physical quantity used to describe the speed and direction of the movement of the particle is a vector quantity.
1) Average velocity: is the ratio of the displacement to the time taken to pass this displacement, which is defined as , and the direction is the same as the direction of the displacement. The average speed can only be roughly described as a variable speed movement.
2) Instantaneous velocity: It is the speed of the particle at a certain time or through a certain position, and the instantaneous velocity is referred to as velocity, which can move precisely at variable speed. The magnitude of instantaneous velocity is referred to as velocity, and it is a scalar quantity.
6. Acceleration: The quantity describes the physical quantity of how fast or slow the velocity changes.
Acceleration is a Bishen vector that moves in the same direction as the amount of change in velocity (note that it has nothing to do with the direction of velocity), and its magnitude is determined by two factors.
Take a look at three or two and solve it.
Read books, headlines and stuff like that.
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