What is the difference between Aristotle s kinematics and Newton s first law?

Aristotle believed that force is what sustains the motion of an object. Force is what makes the state of an object change, and in an ideal state, an object on a smooth horizontal plane is not subjected to force but can maintain motion. Galileo overthrew the purely speculative traditional view of nature represented by Aristotle with systematic experiments and observations, and created modern science based on experimental facts and a rigorous logical system

The foundation was laid for the establishment of Newton's theoretical system.

Newton's first law Any object that is not subject to any external force always remains in a state of uniform linear motion or a state of rest until an external force forces it to change this state.

Since the property of an object to maintain an unchanged state of motion is called inertia, Newton's first law is also called the law of inertia.

The former thinks that the force acts on the object, and the object can move in a uniform straight line: this is in line with common sense, because in reality it is impossible to shield the frictional force, so an external force object that balances with the frictional force can be balanced, so the conclusion is that the force needs to be maintained. The latter describes the uniform motion from the point of view of scientific theory

Ideally, if there is no frictional force, then no external force can be applied to balance the object, so the conclusion is that the motion does not require the maintenance of force. Simple enough.

One is authority and the other is research.

Personally, I think that Aristotle and Newton themselves are more different than they must be.

Aristotle's view is that the motion of an object requires force to sustain it, and without force the object stops moving.

Newton's view: all objects always remain at rest or in a uniform linear motion when they are not subjected to force.

Assuming that the mass of the trolley is m, the total mass of the weight and the weight disc is m, the acceleration megabeam degree is a, and the rope tension force is f, from Newton's second law, it can be obtained

mg-f=ma

f=mamg=ma+ma

Only if m is much less than m, ma is approximately equal to the total gravity mg of the weight and the weight disc.

Encyclopedia, Newton's first law of motion.

1. Definition: When all objects are not affected by external forces, they always maintain a uniform linear motion or a state of rest, which is Newton's first law. 2. Understanding of Newton's First Law:

1.(1) "Everything" means that the law is universal for all objects and is not a special phenomenon. (2) "Not subjected to external forces" is a condition for the law to be established, meaning a

The object is not acted upon by any force (the ideal model, there is no object in real life that is not subject to force); b.The resultant external force on the object is zero, and its effect can be equal to that of not being acted upon. 2.

This law is not an experimental law, but is generalized by further reasoning on the basis of a large number of facts, but the inference has been tested by practice to be correct.

Newton's second law of motion.

Content: The acceleration of an object is directly proportional to the resultant external force on the object, inversely proportional to the mass of the object, and the direction of acceleration is the same as the direction of the resultant external force. Formula; f=ma (unit:

n (N) or kilogram-meter per square second) Newton's original formula: f = d (mv) dt (see Mathematical Principles of Natural Philosophy) The rate of change of momentum of an object with momentum p with time under the action of the resultant force f is equal to the rate of change of the momentum acting on the object. In layman's terms, it is the derivative of the function with t as the independent variable and p as the causal variable, which is the resultant external force on the point.

i.e.: f=dp dt=d(mv) dt (d, which is not delta, but differential. But in the general problems learned in secondary school, there can be no difference between the two) And when the object is moving at a low speed, the speed is much lower than the speed of light, and the mass of the object is a constant that does not depend on the velocity, so there is f=m(dv dt)=ma This is also called the momentum theorem.

In the theory of relativity, f=ma is not valid because the mass changes with velocity, while f=d(mv) dt is still used. From the experiment, it can be found that f m in the case of a certain acceleration, f a in the case of a certain mass (only when f is n in n, m in kg, a in m s 2, f together = ma is true)

The Second Law. 1) Newton's second law is the law of instantaneous action of force. Force and acceleration are generated, changed and dissipated at the same time.

2) f=ma is a vector equation, the positive direction should be specified when applying, where the force or acceleration is the same as the positive direction is taken as a positive value, and the negative value is taken otherwise, and the direction of acceleration is generally taken as the positive direction. (3) According to the principle of independent action of forces, when Newton's second law is used to deal with the problem of the motion of an object in a plane, the forces on the object can be orthogonally decomposed, and the component forms of Newton's second law can be applied in two mutually perpendicular directions: fx=max, fy=may.

Newton's third law of motion.

Contents: The dispersion and reaction forces between two objects, in the same straight line, are equal in magnitude and opposite in direction. (See Newton's third law of motion for details).

f=ma meaning: in the case of a certain acceleration and mass, the magnitude of the acceleration of the object is proportional to the force, inversely proportional to the mass of the object, and proportional to the reciprocal of the mass of the object. The direction of acceleration is the same as that of the applied force.

F=ma is true only when f is in Newtons, m is in kilograms, and A is in m s.

Newton's second law of motion is commonly formulated that the magnitude of an object's acceleration is proportional to the force and inversely proportional to the mass of the object, and is hand-free and proportional to the reciprocal of the mass of the object; The direction of acceleration is the same as the width of the force.

Newton's second law of motion has five characteristics:

Transientness: Newton's second law of motion is the instantaneous effect of force, where acceleration and force are generated, changed and disappeared at the same time.

Vector: <>

is a vector expression, and the direction of acceleration and resultant force is always the same.

Independence: The object is acted on by several external forces, and the acceleration produced under the action of one external force is only related to this external force, independent of other forces, and the vector sum of the acceleration produced by each force is equal to the acceleration produced by the resultant external force, and the resultant acceleration is related to the resultant external force.

Causality: Force is the cause of acceleration, acceleration is the effect of force, so force is the cause of changing the state of motion of an object.

Equivalence is not equivalent: although <>

But <> is not a force, but a reflection of the change in the state of the object; Although <>

It's just <>

The method of measuring the mass of an object, m and <>

or <> irrelevant.

Newton's first law of motion, abbreviated as Newton's first law. Also known as the law of inertia.

A common full formulation: any object must remain in a uniform linear motion or at rest until an external force forces it to change its state of motion.

Newton's Laws of Motion (Newton'S laws of motion) includes Newton's first law of motion, Newton's second law of motion, and Newton's third law of motion.

It was summarized by Isaac Newton in his book "Mathematical Principles of Natural Philosophy" in 1687. Among them, the first law states the meaning of force: force is what changes the state of motion of an object; The second law of the second law states the effect of force:

The force causes the object to gain acceleration; The third law reveals the nature of force: force is an interaction between objects.

The laws in Newton's laws of motion are independent of each other, and their internal logic is self-consistent. Its scope of application is the range of classical mechanics, and the applicable conditions are particles, inertial reference frames, and macroscopic and low-speed motion problems. Newton's laws of motion explain the complete system of Newtonian mechanics and the motion laws of fundamental rolling in classical mechanics, which are widely used in various fields.

Newton's first law gives the concept of an inertial frame, the first.

2. The third law and the system of particle mechanics established by Newton's laws of motion are only true for inertial frames. Therefore, Newton's first law is indispensable and is an important law of mechanics that is completely independent.

Newton's first law is only applicable to the inertial frame of reference, and when the particle is not affected by external forces, the frame of reference that can determine that the particle is stationary or moves in a uniform linear motion must be an inertial frame of reference, so only in the inertial frame of reference is Newton's first law of motion is applicable.

Newton's first law does not apply in a non-inertial frame of reference (i.e., a system with acceleration) because an object that is not subject to an external force may also have acceleration in that frame of reference, which is contrary to Newton's first law.

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Analysis: Newton's Three Laws.

Newton's three laws are important laws in mechanics, and they are the basis for the study of classical mechanics.

1 Newton's First Law.

Contents: Any object remains at rest or in a uniform linear motion until it is forced to change this state by the forces of other objects.

Explanation: Objects have a tendency to maintain rest and move in a uniform linear line, so the motion state of the object is determined by its motion speed, and its motion state will not change without external force. This property of an object is called inertia.

So Newton's first law is also known as the law of inertia. The first law also clarifies the concept of force. It is clarified that force is the interaction between objects, and it is pointed out that it is force that changes the motion state of objects.

Because acceleration describes the change in the state of motion of an object, force is related to acceleration, not to velocity. If you don't pay attention to this in your daily life, you will often have a false impression.

Note: Newton's first law does not hold true in all frames of reference, in fact it only holds in inertial frames of reference. Therefore, whether Newton's first law is true or not is often used as a criterion for whether a frame of reference is an inertial frame of reference.

2 Newton's second law.

Contents: The object will produce acceleration under the action of the resultant external force, and the direction of acceleration is the same as the direction of the resultant external force, and the magnitude of the acceleration is proportional to the magnitude of the resultant external force and the inverse proportion of the inertial mass of the object.

The second law quantitatively describes the effect of the force acting on and quantitatively measures the magnitude of the inertia of an object. It is vector and is an instantaneous relation.

It should be emphasized that the combined external force on the object will produce an acceleration index, which may change the motion state or velocity of the object, but this change is related to the motion state of the object itself.

In a vacuum, since there is no air resistance, various objects have the same acceleration regardless of their mass because they are only subjected to gravity. Therefore, in free fall, their velocity changes the same in the same time interval.

3 Newton's Third Law.

Contents: The action and reaction forces between two objects, on the same straight line, equal in magnitude and opposite in direction.

Note: To change the motion of an object, other objects must interact with it. The interaction between objects is manifested through force.

He also pointed out that the action of force is mutual, and there must be a reaction force. They act on the same straight line, equal in size and opposite in direction.

Also note:

1) There is no priority or priority between action and reaction forces. Creates and disappears at the same time.

2) This pair of forces acts on different objects and cannot be counteracted.

3) The force and reaction force must be forces of the same nature.

4) Nothing to do with the frame of reference.