The first law (that is, the law of inertia)

When any object is not subjected to any external force or force balance (Fnet=0), it always keeps moving in a straight line at a uniform speed or at rest until an external force acts on it, forcing it to change this state.

The second law

Newton's second law is the instantaneous law of force. Force and acceleration occur at the same time, change at the same time, and disappear at the same time.

②F=ma is a vector equation, and the positive direction should be specified when it is applied. All forces or accelerations in the same direction as the positive direction should be positive, and vice versa. In general, the direction of acceleration is positive.

(3) According to the principle of independent action of force, when Newton's second law is used to deal with the motion of an object in a plane, the force acting on the object can be decomposed orthogonally, and the component form of Newton's second law can be applied in two mutually perpendicular directions: Fx=max and Fy=may.

The third law

The expression F=-F' (F stands for acting force, f' stands for reaction force, and negative sign stands for reaction force f' which is opposite to acting force f).

universal gravitation

Newton was the discoverer of the law of universal gravitation, which was mathematically deduced from Kepler's law of planetary motion and other people's research results.

Classical mechanical system

Newton unified the mechanics of objects on the earth and celestial mechanics into a basic mechanical system and established a classical mechanical theoretical system. It correctly reflects the macro motion law of macro objects at low speed and realizes the first great unity of natural science.

Newton bell

Newton pointed out that the viscous resistance of fluid is proportional to the shear rate. If other conditions are the same, the resistance between fluid parts due to lack of lubricity is directly proportional to the separation speed between fluid parts.

2. Mathematical achievements

Newton and Leibniz independently developed calculus. The appearance of calculus has become another important branch in the development of mathematics besides geometry and algebra-mathematical analysis, and further developed into differential geometry, differential equations, variational methods and so on, thus promoting the development of theoretical physics.

In mathematics, one of Newton's widely recognized achievements is the generalized binomial theorem, which is applicable to any power. In addition, Newton discovered Newton's identity and Newton's method, classified cubic curves (bivariate cubic polynomials), made great contributions to finite difference theory, and obtained the solution of Diophantine equation by using fractional exponent and coordinate geometry for the first time.

3. Optical achievements

Newton obtained through prism experiments that white light is a mixture of different colors (that is, different wavelengths), and different wavelengths of light have different refractive indexes. Among visible light, red light has the longest wavelength and the smallest refractive index. Violet light has the shortest wavelength and the largest refractive index. This important discovery of Newton became the basis of spectral analysis and revealed the secret of light color.

Invent the reflective telescope.

4. Hot achievements

Newton established the law of cooling, that is, when there is a temperature difference between the surface of an object and its surroundings, the heat lost per unit area per unit time is directly proportional to this temperature difference.

5. Economic achievements

Newton first proposed the gold standard. The first country to implement the gold coin standard was Britain. 17 17 years, the famous physicist isaac newton set the price of gold per ounce at 3 pounds 17 shillings10.5p during his tenure as director of the British Mint. 18 16, Britain passed the Gold Standard Act, which legally recognized gold as the monetary standard for issuing paper money.

Extended data

Sir isaac newton, president of the Royal Society, is a famous British physicist, an encyclopedic "all-rounder" and author of Mathematical Principles of Natural Philosophy and Optics.

He described gravity and three laws of motion in the paper "Laws of Nature" published by 1687. These descriptions laid the scientific view of the physical world in the next three centuries and became the basis of modern engineering. By demonstrating the consistency between Kepler's law of planetary motion and his theory of gravity, he showed that the movements of ground objects and celestial bodies all follow the same natural law; It provides strong theoretical support for the sun-centered theory and promotes the scientific revolution.

In mechanics, Newton expounded the conservation principle of momentum and angular momentum and put forward Newton's law of motion. In optics, he invented reflecting telescope, and based on the observation that a prism diverges white light into the visible spectrum, he developed the color theory. He also systematically expressed the cooling law and studied the speed of sound.

In mathematics, Newton and Gottfried Wilhelm Leibniz shared the honor of developing calculus. He also proved the generalized binomial theorem and put forward Newton's method to approximate the zero point of function, which contributed to the study of power series.

In economics, Newton put forward the gold standard.

References:

Baidu Encyclopedia isaac newton