أكاديميا - كولنز - معاجم الجيب العلمية - الفيزياء - انكليزي - فرنسي - عربي الحرف ٦_ r

Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic Letter 6_ R


resonance
resonance f

buzz. The system has a large amplitude vibration when it is driven at a frequency close to its natural frequency.
If a person sings a note near a piano, some of the strings buzz, or vibrate (in response) in sympathy. In the same way, the tuning circuit in a radio device does not pass large-amplitude signals unless their frequency is close to its natural value. The buzz was also the cause of the collapse of the Tacoma Narrows Bridge in the United States of America.

A resonance tube allows one to know the speed of sound in the air, as it changes its length until the column of air resonates with a tuning fork of known frequency.


resultant
result f

Outcome. If more than one force is exerted on a stationary body, the body cannot move in more than one direction. If it moves, its movement is as if it were a single force acting on it.

This net external force is the resultant of the actual forces. The equilibrant group of forces is equal to and opposite to the resultant. Here we must note several cases. (See fees in entry equilibrium).

* Forces along one line: The resultant is the sum of these forces in the same direction. The resultant runs along the same line.

* Parallel forces: The resultant is the sum of these forces in the same direction. The resultant operates along a line defined by the law of moments (torques).

Equal forces: The resultant follows the parallel rule
Sides parallelogram rule.
See also .components


right-hand rules
Règle ƒ from the main droite

Right hand bases. Two techniques are used to help one know the direction of magnetic effects. The right-hand grip rule in (a) below (with the fingers) gives the direction of the field around the thumb current. Fleming's right hand rule or right hand dynamo rule in (b) shows the directions of the field, movement, and voltage/current in cases of electromagnetic induction.


ring main
Circuit m en anneau

Toroidal master distribution. A modern home circuit in which the wire runs from the fuse box, passes through a series of 13-amp sockets, and then returns to the fuse box. The main fuse operates at up to 30 amps.
Also called ring circuit.


ripple tank
Basin m d'essai des ondulations

Ripple basin. A device that clearly shows the behavior of water waves. The source of the waves is a submerged vibrating body. The edges of the tub absorb waves to prevent distorted reflections. A lamp located above the glass base of the aquarium displays an image of the waves on a screen.

The ripple trough in the figure below is used to demonstrate the effect of a spaced mirror.


rocket motor
motor m fusee

Rocket engine. An engine that can be used in the depths of space, as the fuel and oxidizer are carried together in the spacecraft.


Rutherford
Rutherford m

Rutherford. Ernest Rutherford (1871 - 1937) A scientist who made many major achievements in the fields of radioactivity and nuclear physics in general. His model of the atom led to the emergence of Niels Bohr's model. Element 104, rutherfordium, was named after him.