Centrifugal Force
Centrifugal force is a special case of fictitious force that appears natural in the context of studying the motion of objects in repositories not inertial. The effect varies due to rotation of these benchmarks and results in a tendency to remove the bodies from the center of rotation. This, for example, the sensation of ejecting a passenger in a vehicle makes a turn.
Summary |
Description
Demonstration of the expression of centrifugal force
The expression of centrifugal force to add is:
where
- a is the acceleration
- m is the mass of the object being studied;
- is the rotational speed of the rotating frame relative to inertial frame;
- R is the distance from the center of rotation at the center of gravity of the object;
all measured from a single non-inertial frame. In the case of a vehicle traveling at a speed v, we have: 
and R is the radius of curvature of the trajectory of the repository
Examples
There are cases where the centrifugal effect can be sought, for example during the drying of clothes in a drum machine; Inevitable for rotating systems, it can be an inconvenience for the passengers of a vehicle negotiating a change of direction, we then resort to tricks to cancel, or rather compensate for this effect: Combination anti-G Pilots fighter aircraft , some of tilting trains , banked roads.
The spinning of linen
It's the easiest job of the centrifugal effect. The rotational movement imposed on the machine also induced accelerations transmitted to the water particles. While they remained glued to the rest, by viscosity to textiles , the cohesive forces become insufficient when the assembly rotates fast enough. The local equilibrium is no longer guaranteed, the water is ejected.
Separation of liquids
It's the same principle used to separate the constituent elements of non-homogeneous liquids such as blood. The force field induced by the centrifugal effect is akin to a stronger gravitational field that promotes separation of components of densities different.
The enrichment of uranium is based on this principle, but is technically more complicated, since it takes "to make the liquid metal" to power the centrifuge. That is to say incorporate atoms of uranium "metal" in a liquid (or gas), such as uranium hexafluoride.
Regulators centrifugal effect (on old steam engines)
The diagram reproduced given the principle regulator of James Watt. Driven through the belt, the machine, the rotor sees its weights deviate. A control rod when a valve. The action on the valve has an inverse effect on the power supplied to the machine: the principle of enslavement. Too quickly closing the steam, it opens too slow, the system will eventually find the right balance, and thus a regulated system.
Example Regulator
Principle of a centrifugal regulator
Tilting Train
Travel by train is often slow. It is nice to be able to move the cars to stretch their legs. The old lines are often winding, and travel along the paths are difficult to negotiate. The idea of tilting train operated by the centrifugal force to tilt the cars, so that the centrifugal force plus the weight to give an apparent weight exactly perpendicular to the floor. Thus passengers no longer feel the shear stresses along the body that tend to lose balance.
In some cases this can increase the speed but the effect is carried over on the tracks that deserve trains. Again it uses the banked turns to resume with greater incidence of centripetal force applied to the axles. This requires a shift in curves at speeds well particular: too low, the train looks inward, too high one is drawn outward.
The relationship to calculate the angle at which the rails are inclined to be: 
Weight
The Earth is not a strictly inertial reference frame. Compared to the geocentric reference system , the Earth is driven by a rotational movement (which also produces the alternating day / night). The bodies on Earth are subjected to centrifugal force and for this reason that the firing of rockets are preferably located near the equator , because that is where the maximum effect (effect "slingshot") in the case of the Kourou Space Centre (approx. 5 latitude North) and Cape Kennedy (approx. 28 latitude North).
This centrifugal force is part of the weight, it does not limit the Earth's gravity.
Round cornering
Plane carrying a turn in the sky
To understand, imagine that the aircraft turns in the same plane (a bit like drawing on the demonstration of the centrifugal force above). The calculation is valid if the aircraft performs a turn toward more "complex".
As shown in the formula above, the centrifugal acceleration (and hence the centrifugal force) is directly related to the linear speed of the device.
F = M * V 2 / R A = V 2 / R since F = M * A according to the Newton formula
Consider an F-14 Tomcat Grumman, capable of flying at 2,485 mph, or a Mig-29, reaching Mach 2.3 (2.3 times the speed of sound) and you'll see a pilot, flying this type of aircraft, take 8 or 9 G (8 or 9 times Earth's gravity).
Fighter pilots are specially trained to collect these extreme acceleration. Moreover, they are equipped with a G-suit to offset the effects they might cause (Red or Black Veil Veil).
These two adverse effects are due to accelerations, the pilot perceives as positive or negative (and I emphasize that it is the driver who receives the acceleration while the latter has not changed (as in picture above)). The Red Veil is a rush of blood to the head as the Black Veil is the reflux of blood into the legs. The G-suit is a set of bags that inflate to block these phenomena.
Vibrating Cell Phone
A small weight is attached eccentrically on the shaft of a micro-motor. Driven at high speed, the centrifugal effect causes the reaction of the bearing that makes the handset vibrate.
Notes
Misconceptions
- Centrifugal force is a reaction to the centripetal force.
- centrifugal force obeys the principle of action-reaction.
- Centrifugal force is a force like the others.
Loading ...