# Tagged Questions

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### slippery slope facts of spherical and plane object [on hold]

Imagine a slippery slope and from the top of the slope I threw two object one is spherical stone and the other is plane box. Why the stone would reach the bottom by rolling randomly where the box ...
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### Why does weight on Earth have a tangential component?

I read in Pulsar's answer of this question that weight has a tangential component due to the rotation of the (assumed spherical) Earth but I don't understand this. Can someone expand on it please?
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### Why is the water still in the glass while rolling?

Pilot drinks glass of water while rolling the plane. The water stays in the glass, even if the plane is upside down. How is this possible? Why doesn't the water leave the glass, as it does when I ...
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### Is there a physical formula or equation to describe change in size of rotating tire?

I've heard that tires will actually grow larger when you are moving, and shrink back down when you stop. I was wondering if there is a way to calculate the size of a given tire, and what the variables ...
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### Lagrangian of an effective potential

If there is a system, described by an Lagrangian $\mathcal{L}$ of the form $$\mathcal{L} = T-V = \frac{m}{2}\left(\dot{r}^2+r^2\dot{\phi}^2\right) + \frac{k}{r},\tag{1}$$ where $T$ is the kinetic ...
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### Why does a velocity that gives gravity's centripetal acceleration make you stay in orbit?

Explanations of basic orbital mechanics that I can find all go, $$\frac{v_{satellite}^2}{r} = a_c = \frac{F_{gravity}}{M_{planet}} = \frac{(\frac{G M_a M_s}{r^2})}{M_{planet}}$$ , and so you get a ...
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### Centrifugal force in the two body problem?

In the two body problem, the Effective radial potential energy in general relativity is given by $$V(r)=-\frac{G M m}{r}+\frac{L^{2}}{2\mu r^{2}}-\frac{G(M+m)L^{2}}{c^{2}\mu r^{3}}$$ where the ...
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### Why does the centrifugal term involve a vector originating from the center of Earth? [closed]

Why in every mechanics/dynamics book I look the centrifugal force due to Earth's rotation is measured from "the center of Earth"? For example in Marion's dynamics, the fixed inertial axes are placed ...
8k views

### Why would a spinning space station create a centrifugal force on an astronaut rather than simply spinning around him/her?

We often see films with spinning space station that create artificial gravity by having the astronauts pulled outwards by centrifugal force. I'd like to know if this would really happen, and if so, ...
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### How is the centrifugal force responsible for Earth's oblateness? [duplicate]

I'm having serious problems understanding the centrifugal force caused by Earth's rotation. How does it affect the Earth's shape? Should I draw the gravitational acceleration (the one in Newton's ...
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### Centripetal and Centrifugal force

If water stays in a pail of water that is whirled around a circular path, the water stays in the pail. But is it because of centripetal force or inertia? I'm getting confused by all the different ...
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### Is it possible to fight tree height limit with centrifugal force?

I heard tree has some height limit because water cannot be pumped over some height (130m if I remember it right) which cap the limit of tallest tree possible on earth But there are centrifugal force ...
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### Strength of the centrifugal force

Let's say you're on a roundabout. When you're radially further away from the roundabout would you feel more centrifugal force or less? I feel like intuitively you'd feel less, but from the actual ...
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### Spinning a string with a mass on the end. What makes the mass rotate parallel to the ground? [closed]

Say you use your hand to rotate a string with a mass attached to the end. The string will first become taunt and then the mass and string will move upwards until they are spinning parallel to the ...
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### Orbiting in space (free fall) and centripetal force?

So basically astronauts are weightless b/c they are free falling. But to get to that state they need to be moving real fast. So why doesn't that speed along with the centripetal force affect them? I ...
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### Meaning of centrifugal term in the mechanical energy of a orbiting planet [duplicate]

For a planet under the effect of gravitational force the mechanical energy can be written as $$E=\frac{1}{2}\mu {\dot{r}}^2+\frac{L^2}{2\mu r^2}-\gamma \frac{m M}{r^2} \tag{1}$$ Where $\mu$ is the ...
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### Why does the water in a bucket stay even when swung around in circular motion? [duplicate]

What are the force that act on the water and which force is responsible to keep the water from falling out?
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### Does the centrifugal force affect stationary objects as seen from the inertial reference frame?

If an object is moving at the same speed as a rotating/accelerating frame of reference it's in contact with but in the opposite direction (making its displacement zero), would such an object be ...
101 views

### A question about the famous bucket experiment

Suppose that we have a bucket containing two liquids with different densities.Suppose also that i connect the bucket with an electric motor and i rotate the bucket. Why when the bucket rotates, the ...
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### Planets potential [duplicate]

I'm a physic student of Italy. I'm moving my first steps in this beautiful world, and as every new entry, my simple and stupid questions are sometimes not so simply resolved. I'm trying to know the ...
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### Gravity changes at the equator due to Earth's spin [duplicate]

If an object weights 100 kilos at the equator how much would it weight if the earth spun twice as fast?
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### When we spin and feel our arms fly, is it the effect of gravity?

If accelerating reference frames can be treated as normal inertial reference frames but with gravity, then for a rotating reference frame, is the centrifugal force = gravity? More specifically, I was ...
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### Gravity and elliptical orbits

All orbits are elliptical and special orbits are circular (like when both bodies have the same mass or when the second body's mass is negligibly small). In a circular orbit centrifugal force (which I ...
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### How do we feel fictitious forces?

Fictitious forces arise because of the acceleration of the frame of reference itself. No real forces act on the object, still the object accelerates. So why it is said that if the earth were to ...
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### Solidifying understanding of centrifugal force at the equator vs poles

I'm just trying to get my head around the physics here and understand exactly what's going on, because there's a lot of conflicting information on the internet. Viewed from an inertial reference ...
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### Conservation of energy in vertical circular motion

Books usually use conservation of energy to solve problems in vertical circular motion. But, principle of conservation of energy for one particle is, If all the $n$ forces $\vec F_i (i=1,2,3,..,n)$...
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### Generation of artificial gravity by rotation

I have been trying hard to understand how Artificial Gravity is produced by Rotating a satellite around its own axis. Thus far, I have understood (probably wrong) that as a satellite is spun, walls ...
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### Centrifugal Force vs Motion (inertia)

Could centrifugal force be appropriately described as motion (inertia)--rather than an (imaginary) force? Could such a change of perspective eliminate much of the common confusion?
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### Weightlessness in Satellites

The following is written in my textbook as the reason for weightlessness felt in satellites: The gravitational pull is counterbalanced by the centripetal force. This introduces two problems: ...
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### Solid settling to the top of solution when centrifuged

I have a mixture of dense particles (about 4x that of water) and not-so-dense particles (maybe the same density of water or slightly less or more dense). When I centrifuge a tube filled with a ...
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### As The World Turns 2

When dinosaurs roamed the Earth was the Earth rotating faster creating less gravity to allow for their size? How much would 100 kg weigh then?
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### Centrifugal force on body in motion in space

I'm trying to understand the motion of a body in space for simulation purposes and wondering if my understanding of centrifugal force is correct. Imagine a body in space with no gravitional/EM forces ...
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### Would there be a “freefall zone” in the centre of a centrifugal artificial gravity?

In the novel Schismatrix, Bruce Sterling writes about people living on the inside of rotating cylinders (similar to Larry Niven's Ringworld and Iain M. Banks' Orbitals, but the atmosphere extends ...
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### Can we decrease the value of $g$ (gravitational pull) without gaining height? [closed]

The value of $g$ on earth surface is $9.8\ \text{m/s}^2$ and when we gain height, then the value of $g$ decreases. Pilots experience same phenomena in air, but can we decrease the value of $g$ by ...
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### Why do we only feel the centrifugal force?

After spending some time researching about the centrifugal force, I now understand that it is needed in a non-inertial reference frame for Newton's Laws to hold true. However, I don't understand why ...
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### Rotation of earth and effect on $g$ [duplicate]

How do we calculate the change in the acceleration due to gravity (consider earth as a uniform sphere) with a change in the rotation speed of earth along its axis? How do we build up a mathematical ...
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### Why centrifugal force results in a circularly rotating motion for a stationary object in the non-rotating frame

My doubt is the following: in a rotating frame of reference you have the centrifugal pseudo force. When you analyze and object in circular motion (due to a rope) in the rotating frame of reference, ...
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### What force does balance centripetal force if centrifugal force doesn't exist in reality?

Which force does balance centripetal force? For example if we are rotating a ball tied with a string then centripetal force is acting inwards. Then which force balances it. I thought it is the ...
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### Explain the centrifugal acceleration using the acceleration composition law

It's been a while since my last contact with physics, and recently i've met a probably very simple problem for which I'm trying to find a very formal explanation. In a "uniform circular motion" where ...
633 views

### How many Gs are my clothes experiencing in my washer? [closed]

During a spin cycle I got curious: How many Gs are at play in my simple washing machine? We can assume the drum is 50 cm wide and spins at 1500 rpm.
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### What is the proper vector form for the Gravity Formula?

We are familiar with the equation for calculating the velocity of an object in orbit given the central mass (or the mass given the orbital velocity): $$\frac{v^2}{r} = \frac{MG}{r^2}$$ I'm trying to ...
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### Is Conservation of Energy maintained when the orbit of a rotating mass increases in diameter?

I read an example where someone was explaining how the law of conservation of energy does not have to be maintained within a rotating mass even though angular momentum is maintained. The given ...
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### How to start an artificial gravity?

I understand how artificial gravity in space stations works. It is by normal force the wall exerts on the foot. But I wonder how to start it in the first place. I just learned about centrifugation ...
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### Centrifugal force in Arthur C. Clarke's Rendezvous with Rama

I'm currently reading Arthur Clarke's Rendezvous with Rama. Rama is a 50 km long, 16 km diameter cylindrical alien artifact that is rotating fast enough to provide a 0.6G artificial gravity on its ...
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### Is the centripetal force a pseudo force? [duplicate]

So I'm having a bit of struggle understanding the origin of the centripetal force. Is the centripetal force a pseudo force? Somebody told me that both the centrifugal and the centripetal forces are ...
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### Why is centrifugal force considered fictitious, when it's the one that feels real to us when we are moving in a circle?

Why is centrifugal force considered fictitious, when it's the one that feels real to us when we are moving in a circle? I understand the explanation regarding the reference frames: if our body is the ...
522 views

### Could a bladeless “Tesla Turbine” type air compressor be used as a high vacuum pump?

I have a wacky idea for a new vacuum pump, I'm trying to figure out why it shouldn't work. I'm interested in learning about Tesla Turbines, specifically when used in reverse as compressors or vacuum ...
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### Circular Motion and Simulated Gravity

People have proposed that a spinning cylindrical shape could be used to simulate gravity. Will gravity be simulated if the cylinder is frictionless? My brain can't seem to wrap around the idea that ...