# What is Centrifugal: Definition and 342 Discussions

In Newtonian mechanics, the centrifugal force is an inertial force (also called a "fictitious" or "pseudo" force) that appears to act on all objects when viewed in a rotating frame of reference. It is directed away from an axis which is parallel to the axis of rotation and passing through the coordinate system's origin. If the axis of rotation passes through the coordinate system's origin, the centrifugal force is directed radially outwards from that axis. The magnitude of centrifugal force F on an object of mass m at the distance r from the origin of a frame of reference rotating with angular velocity ω is:

The concept of centrifugal force can be applied in rotating devices, such as centrifuges, centrifugal pumps, centrifugal governors, and centrifugal clutches, and in centrifugal railways, planetary orbits and banked curves, when they are analyzed in a rotating coordinate system.
Confusingly, the term has sometimes also been used for the reactive centrifugal force, a real inertial-frame-independent Newtonian force that exists as a reaction to a centripetal force.

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1. ### I If centrifugal force doesn't exist, why does a glass move outward in the fridge door?

If centrifugal force dont exist why glass of water moves outward/toward me when I open fridge door? Glass of water moves out in relation to door and in relation to earth, so what force push glass out?

3. ### I Centrifugal separation into hot & cold air streams?

I have been reading about the Ranke-Hilsch vortex tube. Details of the explanation tend to differ somewhat among different sources, but it got me thinking about the following thought experiment. Air enters a tube of about 0.5 x 4 cm cross section. It passes through a section that is channelized...
4. ### I Work done "against centrifugal force"

Consider a merry-go-round (carousel) with a tube fixed radially on it. I use a pole to push a bowling ball slowly through the tube towards the center. (Slowly, so that the kinetic energy is negligible when the ball reaches the center. Also assume zero friction). What happens to the work that I...
5. ### Number of Decks on a Rotating Habitat

My current spaceship design with several ring habitats (6 in my case) works well for worldbuilding purposes, in the sense that the reader should easily be able to tell what types of facilities can be found where on the ship. That’s because the rings distinguish themselves from each other by...
6. ### Converting centrifugal acceleration to frequency

I've calculated this. Is it correct? a=ω²R => ω=√(a/R) T(period)=1/ω=1 / (√(a/R)) f = 1/T = √(a/R) [ if a=10G=100 m/s² ; R=1m ] then: f = √(a/R) = √(100/1) = 10 hertz In angular velocity, can I just convert a=ω²R to ω=√(a/R) and write instead of ω=(2π)/T (in the first line)?
7. ### I How Does Centrifugal Force Affect Objects on a Rotating Disk?

I believe I understand centripetal force, acceleration is necessary for something to spin in a circle because things normally want to continue moving in a straight line (Newton's first law), so a force is necessary to keep something rotating. If you have an object fastened to a rotating disk it...
8. ### I Physics behind making a mango milk shake

Hi Folks!I have limited understanding of physics. I am trying to put into words the working principles of a mixer grinder, specifically for making a mango milkshake. So far, these are the steps I have come up with: Where am I wrong? What things have I gotten right? Thanks!
9. ### B Centrifugal force spinning Basketball

Hi, Looking for Centrifugal force on water droplets on my spinning Basketball at 33 RPM, 45 RPM and 78 RPM
10. ### A Mass dropped onto rotating disk

Picture a flat disk of radius r with a radial vane. The disk is rotating at angular velocity w. Assume the vane is straight, starts at the center and ends at the perimeter of the disk. A very small round mass ( of m grams) is dropped onto the disk very near the center. The vane contacts it and...
11. ### Do centrifugal clutches work in both directions?

As seen by the image below a centrifugal clutch has a pin/hinge in one end of each shoe arm and dependent on the angle of the shoe arm in the fully extended position that will create a wedging action to further increase the friction against the drum beyond the centrifugal force alone. Kind of...
12. ### B Centrifugal Force on Rotating 4" tire / wheel @ 100mph

Heya PhysicsForums! Remote Control Car toy tires and wheels. a 4" tire/wheel rotates at 8400rpm at 100mph. Am wondering how many "g's" the tire "experiences" at that rpm; I imagine it being hundreds of times (if below is accurate am WAY off with my guess) Using a centrifugal force...
13. ### A Centrifugal distortion of a diatomic molecule

Hello! Is it possible for the centrifugal distortion constants (D, H and so on) of a diatomic molecules to be negative? It looks like for high enough vibrational distortions they can be negative, but I don't think I've ever seen that in practice so I was wondering if there is something...
14. ### How does Newton's 1st Law impact centrifugal force? Does it exist?

The reading that I have says that centrifugal force (center fleeing) does not exist
15. ### Measuring the total pressure of a centrifugal compressor

Hello everyone, Nowadays I am planning to redesign my centrifugal compressor which I designed for a subsystem in my graduation project. It's a 3D printed and brushless motor driven centrifugal compressor and its about a hand size. However, due to its relatively small size and relatively low RPM...
16. ### Understanding Powder Behavior under Centrifugal Force

How does powder behave under centrifugal force? Let's imagine that we put the powder in a box and start rotating it. How can I understand how the powder will behave? Will it be flat and stick to the outer side of the box or...?
17. ### Gravitational force equals centrifugal force?

Book says that correct answer is d) but I can't understand why. If the result of gravitational and centrifugal force is 0N then there is no force that would keep those objects inside the spacecraft orbiting around the planet. Or am I just completely wrong? Thank you for your help.
18. ### I Centrifugal Effects During Rail Launch

I’m writing a 3DOF sim for a rocket. I’m having a hard time visualizing centrifugal effects from the Earth's rotation on the rocket while it is moving along the rail (acceleration > 0). I know that once it has left the rail I no longer need to account for it since it’s in the ECI frame and...
19. ### I Is there a negative sign in front of the centrifugal potential energy?

In orbital mechanics, the effective potential is given by ##\frac {1} {2} m r^2 w^2##, which can be expressed in terms of angular momentum ##L## which is conserved. Yet, https://web.njit.edu/~gary/321/Lecture17.html apparently shows the centrifugal potential as the negative of the above...
20. ### B Confusion while trying to build intuition of centripetal force

As I understand it, when a body undergoes uniform circular motion its velocity does not change in magnitude but instead direction. This change in velocity, or acceleration, is directed inward towards the center of the circle. If a body was not experiencing a net centripetal acceleration, then...
21. ### How pressure increases in centrifugal compressor?

I have read this in my textbook about principles of operation of centrifugal compressor: "The impeller is rotated at high speed by the turbine and air is continuously induced into the center of the impeller. Centrifugal action causes it to flow radially outwards along the vanes to the impeller...
22. ### Gravity, heat, flooding, and centrifugal force on a tidal-locked planet

Hi. I'm a science fiction author whose first novel Hemispheres, published through RockHill Publishing, explored a tidal-locked planet (Gliese 581g) where a group of activists increased its rotation to bring daylight cycles to both hemispheres. Now I'm writing the sequel, and there's ecological...
23. ### Coriolis Force and Centrifugal Force

Hello! So for a) I have done the following m = 400t = 400000 kg v = 300 km/h = 83,3 m/s ##\alpha## = 50 (degrees) Now this is the formula for the Coriollis effect $$F = 2 \cdot m (v × \omega)$$ So in a book I found in the library regarding physics I've found a similar example that used...

25. ### Centrifugal pump behavior when the outlet is closed

What would happen if the water pump output or outlet is closed and pump continues running. Will the rotor or impeller inside just rotate and rotate slowly just raising temperature of stuck water in the impeller or would there be sudden increase in pressure immediately damaging the seal. This is...
26. ### Difference between centrifugal force vs reactive centrifugal force?

Difference between centrifugal force vs reactive centrifugal force? and practic example
27. ### Centrifugal forces don't exist in reality?

We can often hear that centrifugal force don't exist in reality...Helicopter mi-26 can lift 56tons ,it has 8 blades,so each blade hold 7 tons of force! Do you know if you put 7tons at blade when blade is not rotating(static) ,bending moment will be way too much and blade will broke at root...
28. ### Belt and Pulleys - Centrifugal Forces

Hi. I assume that vector summation of the centrifugal forces acting on the belt, on pulley A and B, equals to zero. Is Centrifugal force on pulley A static or dynamic force? What would, hypothetically, happen if the sum centrifugal forces acting on the belt are not zero? Could some kind of...
29. ### Calculating Centrifugal & Coriolis Forces at Rest

so I can find the centrifugal force but shouldn't the Coriolis force be 0 because the mass is at rest?
30. ### Does Water Swirl the Other Way in the Southern Hemisphere?

A demonstration of the direction water swirls in two hemispheres Sync the videos yourself: http://toiletswirl.com For the record Destin and I repeat... 2 different Videos synced. The explanation of why water swirls in a specific direction is at about 4 minutes into the video.
31. ### Matt & Hugh play with a Brick and derive Centripetal Acceleration

Matt and Hugh play with a tennis ball and a brick. Then they do some working out to derive the formula for the centripetal force (a = v^2/r) by differentiati...
32. ### Understanding Pseudo-Forces in Non-Inertial Frames

I know that, if my ##X## axis is aligned with the arm, there is friction pointing to ##O## and the ##x## component of the weight. Then, on the ##Y## axis, there is the normal force and the ##y## component of the weight. Supposing that I am situated on the arm (non inertial frame), where is the...
33. ### Coriolis and Centrifugal effects in balance

Hi all, Consider a platform with angular velocity ##\omega##. A particle on top of it has a velocity with only ##\hat \theta## component (no radial ##\hat r## velocity). In this case, the inertial forces read: $$F_{in} = 2m\omega V_\theta \, \hat r + m \omega^2 r \, \hat r$$ If ##V_\theta =...
34. ### I Relativistic centrifugal force

I first thought of this problem when I came across the "Ehrenfest Paradox", and realized that as velocity approaches c, the measured force must diverge to infinity as the velocity approaches c.
35. ### Ideas about centrifugal space colony habitats on high-gravity planets

Centrifuges have long been viewed as the means to provide artificial gravity in the zero-g of deep space. Space colony structures like the O'Neill cylinder and the Stanford torus. Centrifuges could also work their magic on the surfaces of low-gravity planets. Conical or paraboloidal shaped...
36. ### Auto/Motor Centrifugal compressor lift aircraft -- engineering help please

Hello, I have a design for a different type of aircraft. I wanted an actual engineer to give advice before I fork over for some parts to try and make a working model. Attached are some pics. some of the pics are as if it were a full size acft. But for the model I was just going to use two turbo...
37. ### Tangential Component of Centrifugal Acceleration

The thing is in page p.347 Taylor, it is said that the component is: g_tan = Omega^2*Rsin(theta)cos(theta) However the angle between the centrifugal Force and the axis normal to the direction of the grav Force is actually 90 - theta, I am not really getting where I am going wrong understanding...
38. ### Calculating Frictional Torque for a Centrifugal Brake System

Homework Statement Hello, so I currently designing a centrifugal brake, I know how much torque it needs to stop etc just unsure of a few things. How would I calculate frictional torque? I understand that I can use the net torque to determine what torque is needed for equilibrium etc however I...
39. ### I Fictitious forces -- name convention

Hello all, I understand there are four d'Alembert (fictitious) (non-inertial) forces: 1. Coriolis 2. Centrifugal 3. Linear 4. Angular acceleration. But then I think about the Gyroscopic Effect (I understand how it arises, so that is not the issue). I am wondering if one can "classify" these...
40. ### I What is the tangential component? Taylor p.347

I do not understand why the tan component for a gravity affected by the centrifugal force: g = Ω^2 * R * sinθ * cosθ So I tried to draw this: using a "big" X-shaped axis where the / component goes along the main gravity direction while \ points normal to / this direction. Then the centrifugal...
41. ### Why Centrifugal Force in the Derivation of Curvature Drift

Homework Statement This is a question about a pretty basic plasma physics derivation. In the standard derivation of the Curvature Drift of a charged particle in a magnetic field with curvature, the force that they use is the "imaginary" centrifugal force (or the force the guiding center sees in...
42. ### Question About centrifugal force of a moving car

Homework Statement The Actual Question is that: A car is moving on a circular hill with radius R. what is the maximum speed it can have at the apex of the hill such that it doesn't jump of from the hill. I know the solution but I want to know how will be the equations if the velocity is...
43. ### Can Centrifugal Pump Displace Water Down? | Small Manned Submersible

Hello, apologies for the crude drawing. I was wondering if it is possible to have a centrifugal pump that pulls in water and pumps it out down like in the drawn picture? I know usually its to displace water up. I always see centrifugal pumps with discharge oriented up like in the photo. If it...
44. ### Fan Performance and Pressure Distribution in Parallel Centrifugal Fans

I have two different capacity centrifugal Induced Draft fans.I attach them in parallel.They both pull air through the same duct and deliver the exhaust to the same stack. Is the pressure at the inlet and outlet of both fans same? What is the fan curve for such a combination?
45. ### Centrifugal Force Experienced at the Earth's North Pole

If we standing in the equator, then centrifugal force caused by Earth rotation directly balanced by gravity force. But what if we standing in the high altitude or in the pole? In the pole at the distance like 40 km from north pole (so the north pole inside the horizon plane), the gravity have no...
46. ### Why are centrifugal pumps so inefficient?

I have been playing around with pump curves a bit and have noticed that in general, the best operating point yields a pretty poor efficiency relative to the pump input power (75% max). From a second law perspective, there shouldn't be any losses. Where is all of this energy being lost? Is it in...
47. ### Appearence and reality -- centripetal and centrifugal forces....

For each action there is an equal and opposite reaction (third principle), and no one would ever think to say that the action is "real" and the reaction is "apparent". Also the centripetal force is an "action" to which (as it happens for all the actions) it corresponds *always* an equal and...
48. ### Exploring Centrifugal Propulsion: Demystifying the Mechanics and Misconceptions

Hi I am spending time on youtube looking at videos that come up when I search "Centrifugal propulsion" (No need for me to pick a few, you can do a search and see lots.) Most of the videos look poorly made. All show some sort of "vehicle." But the "vehicle" jitters back and forth. I am...
49. ### Shape of water in a rotating container along A vertical axis

Hi! I am currently working on a project that includes rotating a water-filled container. The container is NOT spinning about its vertical axis, but about the vertical axis of the rotating disc. I am aware that the surface shape of water in a rotating bucket takes the shape of a parabola when it...
50. ### I Caculate the reaction force of a radially moving object

Hello, An object moves outward in shaft radially due to centrifugal force. lest say it weights 1kg . in a timestep=0.0001 it travels 0.0017 meters this is actually the difference of two radius, let say first radius r1 = 0.25 meters second r2 = 0.25 + 0.0017 meters rpm of the rotating system...