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natural frequency
frequence of nature

Natural frequency. Any system that exhibits vibration vibrates most freely at one frequency, its natural frequency. The value of this frequency depends on the physical nature of the system. Thus, if a simple pendulum is lifted, it oscillates with a frequency that depends on its length and on the strength of the gravitational field (gravity) in the place. The frequency of the tone produced by blowing at the mouth of a bottle depends on the size and shape of the space inside it.
The previous two examples of resonance match other examples in the fields of electronics, radiation, and nuclear physics, for example. In every system that resonates at its natural frequency, fundamental standing waves are generated. See also sound sources.


neutron
neutron m

Neutron. One of the three main atomic particles. The neutron has no charge, hence the name.) Its mass on the atomic scale is one atomic mass unit (AMU). See nucleon number.

The nucleus of any atom, with the exception of ordinary hydrogen, contains one or more neutrons. Light nuclei have a number of neutrons approximately equal to the number of protons. As for heavy ones, they contain one and a half times more neutrons than protons. These numbers are approximate, because the number of neutrons N can vary over a wide range in relation to the number of protons 2 and the result is a set of isotopes for each element. Tin (50 protons), for example, has 21 isotopes, and the number of its neutrons ranges between 59 and 75.
A neutron.

The neutron is not stable outside the nucleus, but rather tends to decay into a proton and an electron. Or to a beta particle. The half-life period of this decay is about 1000 seconds.


Newton
Newton m

Newton. Isaac Newton) Isaac Newton
(1726 - 1642) is, in the opinion of many, the greatest man in the history of science. His views were linked to actual progress in the fields of physics, mathematics, chemistry, priesthood, and philosophy. His achievements in the field of physics included the study of light, gravity, statics, and kinematics. He gave his name to the force unit in the International System of Units (SI).


Newton's laws of motion
lois fpl de mouvement de Newton

Newton's laws of motion. Three categories link forces to each other and to their effects on objects. It is valid for all forces in all cases and forms the basis of much of physics:

A) The body remains at rest, or its movement continues at a regular speed if it is in motion, unless an unbalanced force acts on it.

b) The rate of change of momentum equals the net force. This law is often written: F = ma.

c) When body A exerts a force on body B, body B exerts a similar force on force A. It is often written as: For every action there is a reaction
Equal and opposite to it.

In cases where the mass of the body is constant, the second law gives us the equation F=ma. Where F is the net effective external force, and is the resulting acceleration. Force and acceleration are both vectors, and therefore they must be in the same direction.

The above equation helps define the unit called “newton”, meaning the unit of force, which is the force that accelerates one kilogram to one meter per square second. See also inertia, equilibrium, and centripetal force.


newton meter
Dynamomètre m

Newton scale. See force meter.