Centrifugal force

In the inertial frame of reference (upper part of the picture), the black ball moves in a straight line. However, the observer (brown dot) who is standing in the rotating/non-inertial frame of reference (lower part of the picture) sees the object as following a curved path due to the Coriolis and centrifugal forces present in this frame.

Centrifugal forceis afictitious forceinNewtonian mechanics(also called an "inertial" or "pseudo" force) that appears to act on all objects when viewed in arotating frame of reference.It appears to be directed radially away from theaxis of rotation.The magnitude of the centrifugal forceFon an object ofmassmat the distancerfrom the axis of a rotating frame of reference withangular velocity $ω$ is: $F=m\omega ^{2}r$

This fictitious force is often applied to rotating devices, such ascentrifuges,centrifugal pumps,centrifugal governors,andcentrifugal clutches,and incentrifugal railways,planetary orbitsandbanked curves,when they are analyzed in anon–inertial reference framesuch as a rotating coordinate system.

As the force of gravity acts in a straight line the term has sometimes also been used for thereactive centrifugal force,a real frame-independent Newtonian force that exists as a reaction to acentripetal forcecausing the free object to follow an angular path against the rotating system.

History

From 1659, theNeo-Latintermvi centrifuga( "centrifugal force" ) is attested inChristiaan Huygens' notes and letters.^[1]^[2]Note, that in Latincentrummeans "center" and‑fugus(fromfugiō) means "fleeing, avoiding". Thus,centrifugusmeans "fleeing from the center" in aliteral translation.

In 1673, inHorologium Oscillatorium,Huygens writes (as translated byRichard J. Blackwell):^[3]

There is another kind of oscillation in addition to the one we have examined up to this point; namely, a motion in which a suspended weight is moved around through the circumference of a circle. From this we were led to the construction of another clock at about the same time we invented the first one. [...] I originally intended to publish here a lengthy description of these clocks, along with matters pertaining to circular motion andcentrifugal force^[a],as it might be called, a subject about which I have more to say than I am able to do at present. But, in order that those interested in these things can sooner enjoy these new and not useless speculations, and in order that their publication not be prevented by some accident, I have decided, contrary to my plan, to add this fifth part [...].

The same year,Isaac Newtonreceived Huygens work viaHenry Oldenburgand replied "I pray you return [Mr. Huygens] my humble thanks [...] I am glad we can expect another discourse of thevis centrifuga,which speculation may prove of good use innatural philosophyandastronomy,as well asmechanics".^[1]^[4]

In 1687, inPrincipia,Newton further developsvis centrifuga( "centrifugal force" ). Around this time, the concept is also further evolved by Newton,Gottfried Wilhelm Leibniz,andRobert Hooke.

In the late 18th century, the modern conception of the centrifugal force evolved as a "fictitious force"arising in a rotating reference.^{[citation needed]}

Centrifugal force has also played a role in debates inclassical mechanicsabout detection of absolute motion. Newton suggested two arguments to answer the question of whetherabsolute rotationcan be detected: the rotatingbucket argument,and therotating spheresargument.^[5]According to Newton, in each scenario the centrifugal force would be observed in the object's local frame (the frame where the object is stationary) only if the frame were rotating with respect to absolute space.

Around 1883,Mach's principlewas proposed where, instead of absolute rotation, the motion of the distant stars relative to the local inertial frame gives rise through some (hypothetical) physical law to the centrifugal force and other inertia effects. Today's view is based upon the idea of an inertial frame of reference, which privileges observers for which the laws of physics take on their simplest form, and in particular, frames that do not use centrifugal forces in their equations of motion in order to describe motions correctly.

Around 1914, the analogy between centrifugal force (sometimes used to createartificial gravity) and gravitational forces led to theequivalence principleofgeneral relativity.^[6]^[7]

Introduction

Centrifugal force is an outward force apparent in arotating reference frame.^[8]^[9]^[10]^[11]It does not exist when a system is described relative to aninertial frame of reference.

All measurements of position and velocity must be made relative to some frame of reference. For example, an analysis of the motion of an object in an airliner in flight could be made relative to the airliner, to the surface of the Earth, or even to the Sun.^[12]A reference frame that is at rest (or one that moves with no rotation and at constant velocity) relative to the "fixed stars"is generally taken to be an inertial frame. Any system can be analyzed in an inertial frame (and so with no centrifugal force). However, it is often more convenient to describe a rotating system by using a rotating frame—the calculations are simpler, and descriptions more intuitive. When this choice is made, fictitious forces, including the centrifugal force, arise.

In a reference frame rotating about an axis through its origin, all objects, regardless of their state of motion, appear to be under the influence of a radially (from the axis of rotation) outward force that is proportional to their mass, to the distance from the axis of rotation of the frame, and to the square of theangular velocityof the frame.^[13]^[14]This is the centrifugal force. As humans usually experience centrifugal force from within the rotating reference frame, e.g. on a merry-go-round or vehicle, this is much more well-known than centripetal force.

Motion relative to a rotating frame results in another fictitious force: theCoriolis force.If the rate of rotation of the frame changes, a third fictitious force (theEuler force) is required. These fictitious forces are necessary for the formulation of correct equations of motion in a rotating reference frame^[15]^[16]and allow Newton's laws to be used in their normal form in such a frame (with one exception: the fictitious forces do not obey Newton's third law: they have no equal and opposite counterparts).^[15]Newton's third law requires the counterparts to exist within the same frame of reference, hence centrifugal and centripetal force, which do not, are not action and reaction (as is sometimes erroneously contended).

Examples

Vehicle driving round a curve

A common experience that gives rise to the idea of a centrifugal force is encountered by passengers riding in a vehicle, such as a car, that is changing direction. If a car is traveling at a constant speed along a straight road, then a passenger inside is not accelerating and, according toNewton's second law of motion,the net force acting on them is therefore zero (all forces acting on them cancel each other out). If the car enters a curve that bends to the left, the passenger experiences an apparent force that seems to be pulling them towards the right. This is the fictitious centrifugal force. It is needed within the passengers' local frame of reference to explain their sudden tendency to start accelerating to the right relative to the car—a tendency which they must resist by applying a leftward force to the car (for instance, a frictional force against the seat) in order to remain in a fixed position inside. Since they push the seat toward the right, Newton's third law says that the seat pushes them towards the left. The centrifugal force must be included in the passenger's reference frame (in which the passenger remains at rest): it counteracts the leftward force applied to the passenger by the seat, and explains why this otherwise unbalanced force does not cause them to accelerate.^[17]However, it would be apparent to a stationary observer watching from an overpass above that the frictional force exerted on the passenger by the seat is not being balanced; it constitutes a net force to the left, causing the passenger to accelerate toward the inside of the curve, as they must in order to keep moving with the car rather than proceeding in a straight line as they otherwise would. Thus the "centrifugal force" they feel is the result of a "centrifugal tendency" caused by inertia.^[18]Similar effects are encountered in aeroplanes androller coasterswhere the magnitude of the apparent force is often reported in "G's".

Stone on a string

If a stone is whirled round on a string, in a horizontal plane, the only real force acting on the stone in the horizontal plane is applied by the string (gravity acts vertically). There is a net force on the stone in the horizontal plane which acts toward the center.

In aninertial frame of reference,were it not for this net force acting on the stone, the stone would travel in a straight line, according toNewton's first law of motion.In order to keep the stone moving in a circular path, acentripetal force,in this case provided by the string, must be continuously applied to the stone. As soon as it is removed (for example if the string breaks) the stone moves in a straight line, as viewed from above. In this inertial frame, the concept of centrifugal force is not required as all motion can be properly described using only real forces and Newton's laws of motion.

In a frame of reference rotating with the stone around the same axis as the stone, the stone is stationary. However, the force applied by the string is still acting on the stone. If one were to apply Newton's laws in their usual (inertial frame) form, one would conclude that the stone should accelerate in the direction of the net applied force—towards the axis of rotation—which it does not do. The centrifugal force and other fictitious forces must be included along with the real forces in order to apply Newton's laws of motion in the rotating frame.

Earth

TheEarthconstitutes a rotating reference frame because it rotatesonce every 23 hours and 56 minutesaround its axis. Because the rotation is slow, the fictitious forces it produces are often small, and in everyday situations can generally be neglected. Even in calculations requiring high precision, the centrifugal force is generally not explicitly included, but rather lumped in with thegravitational force:the strength and direction of the local "gravity"at any point on the Earth's surface is actually a combination of gravitational and centrifugal forces. However, the fictitious forces can be of arbitrary size. For example, in an Earth-bound reference system (where the earth is represented as stationary), the fictitious force (the net of Coriolis and centrifugal forces) is enormous and is responsible for theSunorbiting around the Earth. This is due to the large mass and velocity of the Sun (relative to the Earth).

Weight of an object at the poles and on the equator

If an object is weighed with a simplespring balanceat one of the Earth's poles, there are two forces acting on the object: the Earth's gravity, which acts in a downward direction, and the equal and oppositerestoring forcein the spring, acting upward. Since the object is stationary and not accelerating, there is no net force acting on the object and the force from the spring is equal in magnitude to the force of gravity on the object. In this case, the balance shows the value of the force of gravity on the object.

When the same object is weighed on theequator,the same two real forces act upon the object. However, the object is moving in a circular path as the Earth rotates and therefore experiencing a centripetal acceleration. When considered in an inertial frame (that is to say, one that is not rotating with the Earth), the non-zero acceleration means that force of gravity will not balance with the force from the spring. In order to have a net centripetal force, the magnitude of the restoring force of the spring must be less than the magnitude of force of gravity. This reduced restoring force in the spring is reflected on the scale as less weight — about 0.3% less at the equator than at the poles.^[19]In the Earth reference frame (in which the object being weighed is at rest), the object does not appear to be accelerating; however, the two real forces, gravity and the force from the spring, are the same magnitude and do not balance. The centrifugal force must be included to make the sum of the forces be zero to match the apparent lack of acceleration.

Note:In fact, the observed weight difference is more — about 0.53%. Earth's gravity is a bit stronger at the poles than at the equator, because the Earth isnot a perfect sphere,so an object at the poles is slightly closer to the center of the Earth than one at the equator; this effect combines with the centrifugal force to produce the observed weight difference.^[20]

Derivation

For the following formalism, therotating frame of referenceis regarded as a special case of anon-inertial reference framethat is rotating relative to an inertial reference frame denoted the stationary frame.

Time derivatives in a rotating frame

In a rotating frame of reference, the time derivatives of any vector function $P$ of time—such as the velocity and acceleration vectors of an object—will differ from its time derivatives in the stationary frame. If $P 1 P 2, P 3$ are the components of $P$ with respect to unit vectors $i, j, k$ directed along the axes of the rotating frame (i.e. $P = P 1 i + P 2 j + P 3 k$ ), then the first time derivative $[d P /d t]$ of $P$ with respect to the rotating frame is, by definition, $d P 1 /d t i + d P 2 /d t j + d P 3 /d t k$ .If the absoluteangular velocityof the rotating frame is $ω$ then the derivative $d P /d t$ of $P$ with respect to the stationary frame is related to $[d P /d t]$ by the equation:^[21] ${\frac {\mathrm {d} {\boldsymbol {P}}}{\mathrm {d} t}}=\left[{\frac {\mathrm {d} {\boldsymbol {P}}}{\mathrm {d} t}}\right]+{\boldsymbol {\omega }}\times {\boldsymbol {P}}\,$ where $\times$ denotes thevector cross product.In other words, the rate of change of $P$ in the stationary frame is the sum of its apparent rate of change in the rotating frame and a rate of rotation ${\boldsymbol {\omega }}\times {\boldsymbol {P}}$ attributable to the motion of the rotating frame. The vector $ω$ has magnitude $ω$ equal to the rate of rotation and is directed along the axis of rotation according to theright-hand rule.

Acceleration

Newton's law of motion for a particle of mass $m$ written in vector form is: ${\boldsymbol {F}}=m{\boldsymbol {a}}\,$ where $F$ is the vector sum of the physical forces applied to the particle and $a$ is the absoluteacceleration(that is, acceleration in an inertial frame) of the particle, given by: ${\boldsymbol {a}}={\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\,$ where $r$ is the position vector of the particle (not to be confused with radius, as used above.)

By applying the transformation above from the stationary to the rotating frame three times (twice to ${\textstyle {\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}}$ and once to ${\textstyle {\frac {\mathrm {d} }{\mathrm {d} t}}\left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]}$ ), the absolute acceleration of the particle can be written as: ${\begin{aligned}{\boldsymbol {a}}&={\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}={\frac {\mathrm {d} }{\mathrm {d} t}}{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}={\frac {\mathrm {d} }{\mathrm {d} t}}\left(\left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]+{\boldsymbol {\omega }}\times {\boldsymbol {r}}\ \right)\\&=\left[{\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\right]+{\boldsymbol {\omega }}\times \left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]+{\frac {\mathrm {d} {\boldsymbol {\omega }}}{\mathrm {d} t}}\times {\boldsymbol {r}}+{\boldsymbol {\omega }}\times {\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\\&=\left[{\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\right]+{\boldsymbol {\omega }}\times \left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]+{\frac {\mathrm {d} {\boldsymbol {\omega }}}{\mathrm {d} t}}\times {\boldsymbol {r}}+{\boldsymbol {\omega }}\times \left(\left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]+{\boldsymbol {\omega }}\times {\boldsymbol {r}}\ \right)\\&=\left[{\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\right]+{\frac {\mathrm {d} {\boldsymbol {\omega }}}{\mathrm {d} t}}\times {\boldsymbol {r}}+2{\boldsymbol {\omega }}\times \left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]+{\boldsymbol {\omega }}\times ({\boldsymbol {\omega }}\times {\boldsymbol {r}})\.\end{aligned}}$

Force

The apparent acceleration in the rotating frame is $\left[{\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\right]$ .An observer unaware of the rotation would expect this to be zero in the absence of outside forces. However, Newton's laws of motion apply only in the inertial frame and describe dynamics in terms of the absolute acceleration ${\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}$ .Therefore, the observer perceives the extra terms as contributions due to fictitious forces. These terms in the apparent acceleration are independent of mass; so it appears that each of these fictitious forces, like gravity, pulls on an object in proportion to its mass. When these forces are added, the equation of motion has the form:^[22]^[23]^[24] ${\boldsymbol {F}}-m{\frac {\mathrm {d} {\boldsymbol {\omega }}}{\mathrm {d} t}}\times {\boldsymbol {r}}-2m{\boldsymbol {\omega }}\times \left[{\frac {\mathrm {d} {\boldsymbol {r}}}{\mathrm {d} t}}\right]-m{\boldsymbol {\omega }}\times ({\boldsymbol {\omega }}\times {\boldsymbol {r}})=m\left[{\frac {\mathrm {d} ^{2}{\boldsymbol {r}}}{\mathrm {d} t^{2}}}\right]\.$

From the perspective of the rotating frame, the additional force terms are experienced just like the real external forces and contribute to the apparent acceleration.^[25]^[26]The additional terms on the force side of the equation can be recognized as, reading from left to right, theEuler force $-m\mathrm {d} {\boldsymbol {\omega }}/\mathrm {d} t\times {\boldsymbol {r}}$ ,theCoriolis force $-2m{\boldsymbol {\omega }}\times \left[\mathrm {d} {\boldsymbol {r}}/\mathrm {d} t\right]$ ,and the centrifugal force $-m{\boldsymbol {\omega }}\times ({\boldsymbol {\omega }}\times {\boldsymbol {r}})$ ,respectively.^[27]Unlike the other two fictitious forces, the centrifugal force always points radially outward from the axis of rotation of the rotating frame, with magnitude $m\omega ^{2}r_{\perp }$ ,where $r_{\perp }$ is the component of the position vector perpendicular to ${\boldsymbol {\omega }}$ ,and unlike the Coriolis force in particular, it is independent of the motion of the particle in the rotating frame. As expected, for a non-rotating inertial frame of reference $({\boldsymbol {\omega }}=0)$ the centrifugal force and all other fictitious forces disappear.^[28]Similarly, as the centrifugal force is proportional to the distance from object to the axis of rotation of the frame, the centrifugal force vanishes for objects that lie upon the axis.

Absolute rotation

Three scenarios were suggested by Newton to answer the question of whether the absolute rotation of a local frame can be detected; that is, if an observer can decide whether an observed object is rotating or if the observer is rotating.^[29]^[30]

The shape of the surface of waterrotating in a bucket.The shape of the surface becomes concave to balance the centrifugal force against the other forces upon the liquid.
The tension in a string joining twospheres rotatingabout their center of mass. The tension in the string will be proportional to the centrifugal force on each sphere as it rotates around the common center of mass.

In these scenarios, the effects attributed to centrifugal force are only observed in the local frame (the frame in which the object is stationary) if the object is undergoing absolute rotation relative to an inertial frame. By contrast, in an inertial frame, the observed effects arise as a consequence of the inertia and the known forces without the need to introduce a centrifugal force. Based on this argument, the privileged frame, wherein the laws of physics take on the simplest form, is a stationary frame in which no fictitious forces need to be invoked.

Within this view of physics, any other phenomenon that is usually attributed to centrifugal force can be used to identify absolute rotation. For example, the oblateness of a sphere of freely flowing material is often explained in terms of centrifugal force. Theoblate spheroidshape reflects, followingClairaut's theorem,the balance between containment by gravitational attraction and dispersal by centrifugal force. That the Earth is itself an oblate spheroid, bulging at the equator where the radial distance and hence the centrifugal force is larger, is taken as one of the evidences for its absolute rotation.^[31]

Applications

The operations of numerous common rotating mechanical systems are most easily conceptualized in terms of centrifugal force. For example:

Acentrifugal governorregulates the speed of an engine by using spinning masses that move radially, adjusting thethrottle,as the engine changes speed. In the reference frame of the spinning masses, centrifugal force causes the radial movement.
Acentrifugal clutchis used in small engine-powered devices such as chain saws, go-karts and model helicopters. It allows the engine to start and idle without driving the device but automatically and smoothly engages the drive as the engine speed rises.Inertial drum brake ascendersused inrock climbingand theinertia reelsused in many automobile seat belts operate on the same principle.
Centrifugal forces can be used to generateartificial gravity,as in proposed designs for rotating space stations. TheMars Gravity Biosatellitewould have studied the effects ofMars-level gravity on mice with gravity simulated in this way.
Spin castingandcentrifugal castingare production methods that use centrifugal force to disperse liquid metal or plastic throughout the negative space of a mold.
Centrifugesare used in science and industry to separate substances. In the reference frame spinning with the centrifuge, the centrifugal force induces a hydrostatic pressure gradient in fluid-filled tubes oriented perpendicular to the axis of rotation, giving rise to largebuoyant forceswhich push low-density particles inward. Elements or particles denser than the fluid move outward under the influence of the centrifugal force. This is effectivelyArchimedes' principleas generated by centrifugal force as opposed to being generated by gravity.
Someamusement ridesmake use of centrifugal forces. For instance, aGravitron's spin forces riders against a wall and allows riders to be elevated above the machine's floor in defiance of Earth's gravity.^[32]

Nevertheless, all of these systems can also be described without requiring the concept of centrifugal force, in terms of motions and forces in a stationary frame, at the cost of taking somewhat more care in the consideration of forces and motions within the system.

Other uses of the term

While the majority of the scientific literature uses the termcentrifugal forceto refer to the particular fictitious force that arises in rotating frames, there are a few limited instances in the literature of the term applied to other distinct physical concepts.

In Lagrangian mechanics

One of these instances occurs inLagrangian mechanics.Lagrangian mechanics formulates mechanics in terms ofgeneralized coordinates{q_k}, which can be as simple as the usual polar coordinates $(r,\ \theta )$ or a much more extensive list of variables.^[33]^[34]Within this formulation the motion is described in terms ofgeneralized forces,using in place ofNewton's lawstheEuler–Lagrange equations.Among the generalized forces, those involving the square of the time derivatives {(dq_k ⁄ dt )²} are sometimes called centrifugal forces.^[35]^[36]^[37]^[38]In the case of motion in a central potential the Lagrangian centrifugal force has the same form as the fictitious centrifugal force derived in a co-rotating frame.^[39]However, the Lagrangian use of "centrifugal force" in other, more general cases has only a limited connection to the Newtonian definition.

As a reactive force

In another instance the term refers to thereaction forceto a centripetal force, orreactive centrifugal force.A body undergoing curved motion, such ascircular motion,is accelerating toward a center at any particular point in time. Thiscentripetal accelerationis provided by a centripetal force, which is exerted on the body in curved motion by some other body. In accordance withNewton's third law of motion,the body in curved motion exerts an equal and opposite force on the other body. Thisreactiveforce is exertedbythe body in curved motiononthe other body that provides the centripetal force and its direction is from that other body toward the body in curved motion.^[40]^[41] ^[42]^[43]

This reaction force is sometimes described as acentrifugal inertial reaction,^[44]^[45]that is, a force that is centrifugally directed, which is a reactive force equal and opposite to the centripetal force that is curving the path of the mass.

The concept of the reactive centrifugal force is sometimes used in mechanics and engineering. It is sometimes referred to as justcentrifugal forcerather than asreactivecentrifugal force^[46]^[47]although this usage is deprecated in elementary mechanics.^[48]

Notes

^In Latin:vim centrifugam.

References

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^Yoder, Joella (17 May 2013).A Catalogue of the Manuscripts of Christiaan Huygens including a concordance with his Oeuvres Complètes.BRILL.ISBN 9789004235656.Archivedfrom the original on 16 March 2020.Retrieved12 April2018.
^Blackwell, Richard J. (1986).Christiaan Huygens' the pendulum clock, or, Geometrical demonstrations concerning the motion of pendula as applied to clocks.Ames: Iowa State University Press. p.173.ISBN 978-0-8138-0933-5.
^Œuvres complètes de Christiaan Huygens(in French). Vol. 7. The Hague: M. Nijhoff. 1897. p.325.
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^Julian B. Barbour; Herbert Pfister, eds. (1995).Mach's principle: from Newton's bucket to quantum gravity.Boston: Birkhäuser. p. 69.ISBN 0-8176-3823-7.OCLC 32664808.
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^"Centrifuge".Encyclopædia Britannica.April 30, 2015.
^The Feynman Lectures on Physics Vol. I Ch. 12: Characteristics of Force
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^Jerrold E. Marsden; Tudor S. Ratiu (1999).Introduction to Mechanics and Symmetry: A Basic Exposition of Classical Mechanical Systems.Springer. p. 251.ISBN 978-0-387-98643-2.
^"Centrifugal force".Encyclopædia Britannica. 17 August 2016.Retrieved20 April2017.
^Knight, Judson (2016). Schlager, Neil (ed.).Centripetal Force.Thomson Learning. p. 47.Retrieved19 April2017.{{cite book}}:|work=ignored (help)
^"Curious About Astronomy?"ArchivedJanuary 17, 2015, at theWayback Machine,Cornell University, retrieved June 2007
^Boynton, Richard (2001)."Precise Measurement of Mass"(PDF).Sawe Paper No. 3147.Arlington, Texas: S.A.W.E., Inc. Archived fromthe original(PDF)on 2007-02-27.Retrieved2007-01-21.
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^Taylor (2005). p. 342.
^LD Landau; LM Lifshitz (1976).Mechanics(Third ed.). Oxford: Butterworth-Heinemann. p. 128.ISBN 978-0-7506-2896-9.
^Louis N. Hand; Janet D. Finch (1998).Analytical Mechanics.Cambridge University Press.p. 267.ISBN 978-0-521-57572-0.
^Mark P Silverman (2002).A universe of atoms, an atom in the universe(2 ed.). Springer. p. 249.ISBN 978-0-387-95437-0.
^Taylor (2005). p. 329.
^Cornelius Lanczos (1986).The Variational Principles of Mechanics(Reprint of Fourth Edition of 1970 ed.). Dover Publications. Chapter 4, §5.ISBN 978-0-486-65067-8.
^Morton Tavel (2002).Contemporary Physics and the Limits of Knowledge.Rutgers University Press.p. 93.ISBN 978-0-8135-3077-2.Noninertial forces, like centrifugal and Coriolis forces, can be eliminated by jumping into a reference frame that moves with constant velocity, the frame that Newton called inertial.
^Louis N. Hand; Janet D. Finch (1998).Analytical Mechanics.Cambridge University Press. p. 324.ISBN 978-0-521-57572-0.
^I. Bernard Cohen; George Edwin Smith (2002).The Cambridge companion to Newton.Cambridge University Press. p. 43.ISBN 978-0-521-65696-2.
^Simon Newcomb (1878).Popular astronomy.Harper & Brothers. pp.86–88.
^Myers, Rusty L. (2006).The basics of physics.Greenwood Publishing Group. p.57.ISBN 978-0-313-32857-2.
^For an introduction, see for exampleCornelius Lanczos (1986).The variational principles of mechanics(Reprint of 1970 University of Toronto ed.). Dover. p. 1.ISBN 978-0-486-65067-8.
^For a description of generalized coordinates, seeAhmed A. Shabana (2003)."Generalized coordinates and kinematic constraints".Dynamics of Multibody Systems(2 ed.). Cambridge University Press. p. 90ff.ISBN 978-0-521-54411-5.
^Christian Ott (2008).Cartesian Impedance Control of Redundant and Flexible-Joint Robots.Springer. p. 23.ISBN 978-3-540-69253-9.
^Shuzhi S. Ge; Tong Heng Lee; Christopher John Harris (1998).Adaptive Neural Network Control of Robotic Manipulators.World Scientific. pp. 47–48.ISBN 978-981-02-3452-2.In the aboveEuler–Lagrange equations,there are three types of terms. The first involves the second derivative of the generalized co-ordinates. The second is quadratic in ${\boldsymbol {\dot {q}}}$ where the coefficients may depend on ${\boldsymbol {q}}$ .These are further classified into two types. Terms involving a product of the type ${{\dot {q}}_{i}}^{2}$ are calledcentrifugal forceswhile those involving a product of the type ${\dot {q}}_{i}{\dot {q}}_{j}$ fori ≠ jare calledCoriolis forces.The third type is functions of ${\boldsymbol {q}}$ only and are calledgravitational forces.
^R. K. Mittal; I. J. Nagrath (2003).Robotics and Control.Tata McGraw-Hill. p. 202.ISBN 978-0-07-048293-7.
^T Yanao; K Takatsuka (2005)."Effects of an intrinsic metric of molecular internal space".In Mikito Toda; Tamiki Komatsuzaki; Stuart A. Rice; Tetsuro Konishi; R. Stephen Berry (eds.).Geometrical Structures Of Phase Space In Multi-dimensional Chaos: Applications to chemical reaction dynamics in complex systems.Wiley. p. 98.ISBN 978-0-471-71157-5.As is evident from the first terms..., which are proportional to the square of ${\dot {\phi }}$ ,a kind of "centrifugal force" arises... We call this force "democratic centrifugal force". Of course, DCF is different from the ordinary centrifugal force, and it arises even in a system of zero angular momentum.
^See p. 5 inDonato Bini; Paolo Carini; Robert T Jantzen (1997)."The intrinsic derivative and centrifugal forces in general relativity: I. Theoretical foundations".International Journal of Modern Physics D(Submitted manuscript).6(1): 143–198.arXiv:gr-qc/0106014v1.Bibcode:1997IJMPD...6..143B.doi:10.1142/S021827189700011X.S2CID 10652293..The companion paper isDonato Bini; Paolo Carini; Robert T Jantzen (1997)."The intrinsic derivative and centrifugal forces in general relativity: II. Applications to circular orbits in some stationary axisymmetric spacetimes".International Journal of Modern Physics D(Submitted manuscript).6(1): 143–198.arXiv:gr-qc/0106014v1.Bibcode:1997IJMPD...6..143B.doi:10.1142/S021827189700011X.S2CID 10652293.
^Mook, Delo E.; Thomas Vargish (1987).Inside relativity.Princeton, N.J.: Princeton University Press. p. 47.ISBN 0-691-08472-6.OCLC 16089285.
^G. David Scott (1957)."Centrifugal Forces and Newton's Laws of Motion".Vol. 25. American Journal of Physics. p. 325.
^ Signell, Peter (2002)."Acceleration and force in circular motion"Physnet.Michigan State University, "Acceleration and force in circular motion", §5b, p. 7.
^Mohanty, A. K. (1994).Fluid mechanics(2nd ed.). New Delhi: Prentice-Hall of India. p. 121.ISBN 81-203-0894-8.OCLC 44020947.
^Roche, John (September 2001)."Introducing motion in a circle"(PDF).Physics Education.43(5): 399–405.Bibcode:2001PhyEd..36..399R.doi:10.1088/0031-9120/36/5/305.S2CID 250827660.
^Lloyd William Taylor (1959)."Physics, the pioneer science".American Journal of Physics.1(8): 173.Bibcode:1961AmJPh..29..563T.doi:10.1119/1.1937847.
^Edward Albert Bowser (1920).An elementary treatise on analytic mechanics: with numerous examples(25th ed.). D. Van Nostrand Company. p. 357.
^Joseph A. Angelo (2007).Robotics: a reference guide to the new technology.Greenwood Press. p. 267.ISBN 978-1-57356-337-6.
^Eric M Rogers (1960).Physics for the Inquiring Mind.Princeton University Press. p.302.

External links

Media related toCentrifugal forceat Wikimedia Commons

[4] In Latin:vim centrifugam.

[yoeder-1] Yoder, Joella(1991)."Christiaan Huygens' Great Treasure"(PDF).Tractrix.3:1–13.Archived(PDF)from the original on 13 April 2018.Retrieved12 April2018.

[Yoder2013-2] Yoder, Joella (17 May 2013).A Catalogue of the Manuscripts of Christiaan Huygens including a concordance with his Oeuvres Complètes.BRILL.ISBN 9789004235656.Archivedfrom the original on 16 March 2020.Retrieved12 April2018.

[3] Blackwell, Richard J. (1986).Christiaan Huygens' the pendulum clock, or, Geometrical demonstrations concerning the motion of pendula as applied to clocks.Ames: Iowa State University Press. p.173.ISBN 978-0-8138-0933-5.

[5] Œuvres complètes de Christiaan Huygens(in French). Vol. 7. The Hague: M. Nijhoff. 1897. p.325.

[Newton-6] An English translation is found atIsaac Newton (1934).Philosophiae naturalis principia mathematica(Andrew Motte translation of 1729, revised by Florian Cajori ed.). University of California Press. pp. 10–12.ISBN 9780520009271.

[Barbour-7] Julian B. Barbour; Herbert Pfister, eds. (1995).Mach's principle: from Newton's bucket to quantum gravity.Boston: Birkhäuser. p. 69.ISBN 0-8176-3823-7.OCLC 32664808.

[Eriksson-8] Science education in the 21st century.Ingrid V. Eriksson. New York: Nova Science Publishers. 2008.ISBN 978-1-60021-951-1.OCLC 165958146.{{cite book}}:CS1 maint: others (link)

[9] Richard T. Weidner and Robert L. Sells (1973).Mechanics, mechanical waves, kinetic theory, thermodynamics(2 ed.). Allyn and Bacon. p. 123.

[10] Restuccia, S.; Toroš, M.; Gibson, G. M.; Ulbricht, H.; Faccio, D.; Padgett, M. J. (2019)."Photon Bunching in a Rotating Reference Frame".Physical Review Letters.123(11): 110401.arXiv:1906.03400.Bibcode:2019PhRvL.123k0401R.doi:10.1103/physrevlett.123.110401.PMID 31573252.S2CID 182952610.

[Taylor1-11] John Robert Taylor (2004).Classical Mechanics.Sausalito CA: University Science Books. Chapter 9, pp. 344 ff.ISBN 978-1-891389-22-1.

[12] Kobayashi, Yukio (2008). "Remarks on viewing situation in a rotating frame".European Journal of Physics.29(3): 599–606.Bibcode:2008EJPh...29..599K.doi:10.1088/0143-0807/29/3/019.S2CID 120947179.

[13] David P. Stern (2006)."Frames of Reference: The Basics".From Stargazers to Starships.Goddard Space Flight Center Space Physics Data Facility. Archived fromthe originalon 6 April 2020.Retrieved20 April2017.

[14] "Centrifuge".Encyclopædia Britannica.April 30, 2015.

[15] The Feynman Lectures on Physics Vol. I Ch. 12: Characteristics of Force

[Fetter-16] Alexander L. Fetter;John Dirk Walecka(2003).Theoretical Mechanics of Particles and Continua.Courier Dover Publications. pp. 38–39.ISBN 978-0-486-43261-8.

[Marsden-17] Jerrold E. Marsden; Tudor S. Ratiu (1999).Introduction to Mechanics and Symmetry: A Basic Exposition of Classical Mechanical Systems.Springer. p. 251.ISBN 978-0-387-98643-2.

[EB-18] "Centrifugal force".Encyclopædia Britannica. 17 August 2016.Retrieved20 April2017.

[Science_of_Everyday_Things-19] Knight, Judson (2016). Schlager, Neil (ed.).Centripetal Force.Thomson Learning. p. 47.Retrieved19 April2017.{{cite book}}:|work=ignored (help)

[20] "Curious About Astronomy?"ArchivedJanuary 17, 2015, at theWayback Machine,Cornell University, retrieved June 2007

[Boynton-21] Boynton, Richard (2001)."Precise Measurement of Mass"(PDF).Sawe Paper No. 3147.Arlington, Texas: S.A.W.E., Inc. Archived fromthe original(PDF)on 2007-02-27.Retrieved2007-01-21.

[Synge-22] John L. Synge; Byron A. Griffith (2007).Principles of Mechanics(Reprint of Second Edition of 1942 ed.). Read Books. p. 347.ISBN 978-1-4067-4670-9.

[23] Taylor (2005). p. 342.

[L&L_A-24] LD Landau; LM Lifshitz (1976).Mechanics(Third ed.). Oxford: Butterworth-Heinemann. p. 128.ISBN 978-0-7506-2896-9.

[Hand_A-25] Louis N. Hand; Janet D. Finch (1998).Analytical Mechanics.Cambridge University Press.p. 267.ISBN 978-0-521-57572-0.

[Silverman-26] Mark P Silverman (2002).A universe of atoms, an atom in the universe(2 ed.). Springer. p. 249.ISBN 978-0-387-95437-0.

[27] Taylor (2005). p. 329.

[Lanczos_A-28] Cornelius Lanczos (1986).The Variational Principles of Mechanics(Reprint of Fourth Edition of 1970 ed.). Dover Publications. Chapter 4, §5.ISBN 978-0-486-65067-8.

[Tavel-29] Morton Tavel (2002).Contemporary Physics and the Limits of Knowledge.Rutgers University Press.p. 93.ISBN 978-0-8135-3077-2.Noninertial forces, like centrifugal and Coriolis forces, can be eliminated by jumping into a reference frame that moves with constant velocity, the frame that Newton called inertial.

[30] Louis N. Hand; Janet D. Finch (1998).Analytical Mechanics.Cambridge University Press. p. 324.ISBN 978-0-521-57572-0.

[31] I. Bernard Cohen; George Edwin Smith (2002).The Cambridge companion to Newton.Cambridge University Press. p. 43.ISBN 978-0-521-65696-2.

[32] Simon Newcomb (1878).Popular astronomy.Harper & Brothers. pp.86–88.

[33] Myers, Rusty L. (2006).The basics of physics.Greenwood Publishing Group. p.57.ISBN 978-0-313-32857-2.

[Lanczos-34] For an introduction, see for exampleCornelius Lanczos (1986).The variational principles of mechanics(Reprint of 1970 University of Toronto ed.). Dover. p. 1.ISBN 978-0-486-65067-8.

[Shabana1-35] For a description of generalized coordinates, seeAhmed A. Shabana (2003)."Generalized coordinates and kinematic constraints".Dynamics of Multibody Systems(2 ed.). Cambridge University Press. p. 90ff.ISBN 978-0-521-54411-5.

[Ott-36] Christian Ott (2008).Cartesian Impedance Control of Redundant and Flexible-Joint Robots.Springer. p. 23.ISBN 978-3-540-69253-9.

[Ge-37] Shuzhi S. Ge; Tong Heng Lee; Christopher John Harris (1998).Adaptive Neural Network Control of Robotic Manipulators.World Scientific. pp. 47–48.ISBN 978-981-02-3452-2.In the aboveEuler–Lagrange equations,there are three types of terms. The first involves the second derivative of the generalized co-ordinates. The second is quadratic in ${\boldsymbol {\dot {q}}}$ where the coefficients may depend on ${\boldsymbol {q}}$ .These are further classified into two types. Terms involving a product of the type ${{\dot {q}}_{i}}^{2}$ are calledcentrifugal forceswhile those involving a product of the type ${\dot {q}}_{i}{\dot {q}}_{j}$ fori ≠ jare calledCoriolis forces.The third type is functions of ${\boldsymbol {q}}$ only and are calledgravitational forces.

[Nagrath-38] R. K. Mittal; I. J. Nagrath (2003).Robotics and Control.Tata McGraw-Hill. p. 202.ISBN 978-0-07-048293-7.

[Toda-39] T Yanao; K Takatsuka (2005)."Effects of an intrinsic metric of molecular internal space".In Mikito Toda; Tamiki Komatsuzaki; Stuart A. Rice; Tetsuro Konishi; R. Stephen Berry (eds.).Geometrical Structures Of Phase Space In Multi-dimensional Chaos: Applications to chemical reaction dynamics in complex systems.Wiley. p. 98.ISBN 978-0-471-71157-5.As is evident from the first terms..., which are proportional to the square of ${\dot {\phi }}$ ,a kind of "centrifugal force" arises... We call this force "democratic centrifugal force". Of course, DCF is different from the ordinary centrifugal force, and it arises even in a system of zero angular momentum.

[Bini1997-40] See p. 5 inDonato Bini; Paolo Carini; Robert T Jantzen (1997)."The intrinsic derivative and centrifugal forces in general relativity: I. Theoretical foundations".International Journal of Modern Physics D(Submitted manuscript).6(1): 143–198.arXiv:gr-qc/0106014v1.Bibcode:1997IJMPD...6..143B.doi:10.1142/S021827189700011X.S2CID 10652293..The companion paper isDonato Bini; Paolo Carini; Robert T Jantzen (1997)."The intrinsic derivative and centrifugal forces in general relativity: II. Applications to circular orbits in some stationary axisymmetric spacetimes".International Journal of Modern Physics D(Submitted manuscript).6(1): 143–198.arXiv:gr-qc/0106014v1.Bibcode:1997IJMPD...6..143B.doi:10.1142/S021827189700011X.S2CID 10652293.

[Mook-41] Mook, Delo E.; Thomas Vargish (1987).Inside relativity.Princeton, N.J.: Princeton University Press. p. 47.ISBN 0-691-08472-6.OCLC 16089285.

[Scott-42] G. David Scott (1957)."Centrifugal Forces and Newton's Laws of Motion".Vol. 25. American Journal of Physics. p. 325.

[Signell-43] Signell, Peter (2002)."Acceleration and force in circular motion"Physnet.Michigan State University, "Acceleration and force in circular motion", §5b, p. 7.

[44] Mohanty, A. K. (1994).Fluid mechanics(2nd ed.). New Delhi: Prentice-Hall of India. p. 121.ISBN 81-203-0894-8.OCLC 44020947.

[Roche-45] Roche, John (September 2001)."Introducing motion in a circle"(PDF).Physics Education.43(5): 399–405.Bibcode:2001PhyEd..36..399R.doi:10.1088/0031-9120/36/5/305.S2CID 250827660.

[46] Lloyd William Taylor (1959)."Physics, the pioneer science".American Journal of Physics.1(8): 173.Bibcode:1961AmJPh..29..563T.doi:10.1119/1.1937847.

[Bowser-47] Edward Albert Bowser (1920).An elementary treatise on analytic mechanics: with numerous examples(25th ed.). D. Van Nostrand Company. p. 357.

[Angelo-48] Joseph A. Angelo (2007).Robotics: a reference guide to the new technology.Greenwood Press. p. 267.ISBN 978-1-57356-337-6.

[Rogers-49] Eric M Rogers (1960).Physics for the Inquiring Mind.Princeton University Press. p.302.

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