أكاديميا - كولنز - معاجم الجيب العلمية - الفيزياء - انكليزي - فرنسي - عربي الحرف ٣_ c

Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic Letter 3_ C


center of mass
Center m de masse

Center of mass. A point of a body or system where we can often think of its mass as being concentrated. We can think of the sun, planets, and moons as point masses as far as their movements and the forces between them are concerned.

The center of mass of a simple body is located at its geometric center, which is symbolized by it in the cases shown below.


centrifugal force
force f centrifuge

Centrifugal force. A force that may be noticeable during movement in a curve. Thus, people in a car turning a corner feel that they are being pushed away from the center of the curve. In fact, their bodies are trying to move in a straight line, and they are really being pushed toward the center of the curve by the side of the car (see centripetal force).

Power from the vehicle

The repulsive force is not a real force, and it is best to avoid using this term.


centripetal force
Force centripète

Centripetal force. A body cannot accelerate unless a net external force acts on it. The body is in a state of equilibrium and does not move, or it moves at a constant speed in a straight line. To force the body to follow a curved line, there must be a force pushing towards the center. This force is called centripetal (meaning seeking towards the center -cen tre - seeking). A body that is rotating in a circle along a string or string is pulled to the center by the tension of the string. If the string breaks, the body continues its movement in a straight line.

When a car moves in a curve, the friction between the street ground and the tires gives the necessary force. Gravity is the centripetal force in the case of orbiting objects.


chain reaction
Reaction in chain

Chain reaction. A situation in which one event leads to causing another, which causes a third, and so on. An important example of this is nuclear fission. Neutrons are among the products of the fission of a nucleus 2350 (see uranium). If a neutron strikes the nucleus of 235 correctly, it can cause it to fission in turn, producing more neutrons, and so the chain continues on its path.

If the neutrons released by fission are caused
If more than one new fission occurs on average, the chain reaction consumes itself.” This is what happens in an atomic bomb. In the case of nuclear power, the design is such that the neutrons emitted by each fission cause only one additional fission on average.


charge. charge
charge f

Shipment. A distinctive characteristic of subatomic particles. Tests show the existence of two types of charges, called: positive charge (as in the proton) and negative charge (as in the electron). We find that the two opposite charges attract each other, while the two identical charges repel each other.

Ordinary atoms contain equal numbers of protons and electrons, and these 6 atoms are neutral, with no net charge. Ions are atoms that contain too few or too many electrons. This is why a piece of matter containing many electrolytes appears to have a net charge. See static electricity. A moving charge, called a current, involves the transfer of energy.

The unit of charge Q is the coulomb, C. It is the charge carried by about 1019 x 1.6 electrons - the charge carried by one ampere in one second.