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

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


force meter
Dynamomètre m

A dynamometer is a device used to measure force. All types of spring balances are force balances, where an unknown force is balanced by the spring stress. The amount of change in the length of the spring relative to the unit of force applied to it is known by the test.
Also called Newton meter.


force ratio
Rapport m de forces

Power ratio. In a machine, it is the power output (load) divided by the applied force (input or effort). The power ratio is usually called the mechanical advantage. It has no symbol or unit.


fossil fuel
carburetor m fossile

fossil fuel. Includes coal, oil, natural gas and peat. These fuels were formed over thousands of years as a result of the decomposition of animal and plant remains. There is a global interest in preserving stocks of these rapidly depleting fuels.


Foucault pendulum
pendule m de Foucault

Foucault's pendulum. A very long pendulum that appears to be flat
Its movement changes with the Earth's rotation. Foucault demonstrated this effect in Paris in 1851. There is a famous pendulum in the Science Museum in London.


free fall
chute f libre

Free fall . A body is in free fall if the only external force acting on it is the force of gravity. Then the body appears weightless. The Earth exists in a state of free fall around the Sun, and this is the case of a large rock falling into an abyss. In cases like the last one, we can often ignore air friction.

During free fall, the body moves with a constant acceleration equal to 9. Near the ground, 9 is about 85 m/s2.
We approach ballistics, which is the study of the movement of the projected body, by finding the horizontal and vertical components of the movement. The vertical component involves free fall while the horizontal component is stationary. See weight.


frequency (f)
frequence f

Frequency The number of cycles of a periodic motion in a unit of time, such as the number of waves passing a point in a second, or the number of pendulum cycles per minute. The unit of frequency in the International System of Units (SI) is hertz, Hz, revolutions per minute.

The magnitudes of the wave's frequency f, its wavelength, and its speed are related to each other according to the wave equation:
c = fx


friction
frottement m

Friction is a force that tends to prevent movement between surfaces. Sometimes friction is useful and works to our advantage. Friction, for example, prevents our feet from slipping while walking, just as it prevents a car's wheels from slipping while it is driving. These two examples indicate how friction works to our advantage.

However, friction slows down movement, wastes energy, produces heat, and causes wear. This is one of the harmful effects of friction.

Horizontally calibrated spring balance
Wooden block
Static and sliding friction

If you gently pull a block on a surface as shown above, nothing happens at first, as the block does not move. That is, P = F. After a little gradually increasing P (drag), a maximum value is obtained, representing static friction or starting friction. Then the mass begins to move, and the value of P, which keeps the mass in motion, is less than the value of static friction. This is called kinetic or sliding friction.

If weights are placed on top of the wooden block, the value of the sliding friction force increases proportionately. God and friction are effects of adhesion.

In some experiments, the runway tilts slightly to compensate for friction. If you give a cart a light push, it continues to move at a constant speed.

It is clear that frictionless movement is a great advantage for transportation modes such as trains. Attempts to achieve frictionless motion include the use of airbags (Hovercraft), magnetic suspension, or slippery objects - in laboratories - on hundreds of small ball bearings.

Even the smoothest surfaces are rough to look at
By microscope.

A lubricant that separates the two surfaces

Wooden block
to push
The smoothest surface is rough when viewed under a microscope


full wave rectification
Redressement m double alternance

Full wave rectification. See rectifier.