Robittybob1

Your diagram shows motion radially out for two situations one with no rotation and the other in a rotating system (with some restraint (like Mike's radial tubes)). A third situation would be like a rocket might be thought as being launched at a radial to the Earth (from the perspective of those standing under it) but from a distance there is also the motion reflecting the Earth's rotation.

You could be right about that too, but then we'd have to back to the OP and see where the idea of centrifugal force came into the discussion.

We also said the equal and opposite forces are not acting on the same object so they can never cancel each other out. So while the centripetal force is acting on the mass, the mass travels in a circle around the central point. The centrifugal force is acting on the center. So we are in agreement on that, in that there is only one force acting on the object. I agree the centrifugal force is not acting on the object. An arc (part of a circle) would have tangents so you don't need a circle to have a tangent.A pendulum would have tangents, so just part of a curve will do. Google definition of tangent:

But we did have a center point and a rotation about that point, so there are infinite radii and infinite tangents. The tangential line is not dependent on the rate of rotation, but radial length and center point. I like Mike's diagram and I'll wait to see where the thread goes before setting up another discussing something similar. But didn't you say centrifugal force was the equal and opposite force to the centripetal force? What is the opposing force to the centripetal force otherwise? So can you have one and not the other? Idea! The moment the centripetal force stops the centrifugal force stops so the object has no forces on it from that time on and hence travels in a straight line. (That is one of Newton's Laws isn't it.)

Good one Mike. But remember if you had that situation as the mass stretches the spring the rate of rotation will slow.

Why would tangential ever stop being tangential? I know radial is harder to define. Thanks I'll do that, for I think I've come up with something strange.

The Tangential velocity stays constant but I am measuring the distance from the center point, which is the length of the Hypotenuse, calculated by the Pythagoras Formula. The length of this hypotenuse starts off as "r" which is one side of the right angled triangle and velocity * time is the other (along the tangent). This distance increases at a non-linear rate and distance from the center over time has a speeding up curvature. This is always radial (i.e. joins the center point to the object) At all times the mass travelling along the tangent line at the time of "release" will also be on a line that is along the same radius. The way this can happen is the rotation rate declines (but this is the rotation rate required if the object was reattached at that point. I am trying to show that relationship with maths. I have seen similar math used to calculate angular momentum of unattached objects.) (This could be wrong as the tangential velocity will be added to the orbital velocity (will it or won't it?), that will give me something to work on.) This works if there is a mass less center wheel (assume string has no mass and the turntable has no mass either). If it has mass its rotational inertia would resist the slowing that is possible with the mass less system i.e one without angular momentum.

That is the basis of the math I'm trying out for as the travelling mass follows the tangent the rate of rotation of the center will decrease to keep the angular momentum of the travelling mass the same (well that is the concept.) It looked as if the position of the travelling mass, the point it departed from the perimeter and the center point always remains in a straight line. That was if the rotating center had no mass but just a rotational rate (that rapidly decreases to close to zero.) So in effect it looks as if it is moving radially from the departure point. It the central object has mass it will not slow down simply because something has separated from it. Yes it will as long as the rotation rate of the core drops to virtually zero over the first 1/4 of the rotation. So the attachment point and the center stays inline with the mass. But there are virtually no physical situations where the center system will have no mass. To get the object moving the forces have to be more than just centripetal forces. You won't get tangential velocity just from centripetal force. The distance keeps on increasing and also the rate it moves away increases too. How it ties in with centripetal motion is that I think it will show that the tangential vector component of the motion will be the velocity needed to keep the angular momentum constant. I'm not that good at doing the math but I'm still working on it.

"Normal" in what way?

I am doing some math that shows the ball goes off in a direction that the distance from the center keeps increasing. The distance from the center increases rapidly to begin with, then slowly up to the value of its velocity away from the center. (I would like to introduce gravitational attraction to make the path curved rather than straight.)

The answer is that there are no metal objects but plenty of other things so you get a dish put one at a time into it and float it in a plastic bucket of water, and see which one aligns with the Earth's magnetic field.

How can the scales be dropping away when they are firmly on the surface?

If the centripetal force and the centrifugal are equal and opposite, how can one be real but not the other? The centrifugal force is acting on the center. It is acting on the center, not on itself. It is a force pulling the center to itself.

Yes I did see something like that in Google images yesterday. The one I wanted is not coming up but this one is close https://s3.amazonaws.com/s3.frank.itlab.us/photo-essays/small/sep_03_0146_white_coral.jpg

That was really good. So can we say the centripetal force acts on the weight orbiting the center and the centrifugal force acts on the center? On shortening the string, or speeding up the rotation, both the centripetal and centrifugal forces increase.

Newton's third law: http://www.physicsclassroom.com/class/newtlaws/Lesson-4/Newton-s-Third-Law So what is the force paired with the centripetal force?

Do you think there is a speed of orbit that will snap the string? What is the centripetal force acting on as the rate of orbit goes up? The mass stays the same. centripetal force F = m * v^2 / r.

If the water came out of the shower hotter than boiling it could get really steamy.

If the centripetal force was greater than the centrifugal force the string would get shortened or if the centrifugal force got greater than the centripetal force the string would stretch or even break and the weight would fly off on a tangent depending on the velocity at the time. it has to do with frames of reference. In your case the center point is not rotating with the mass, but if it was the ball would always be in front of your face and at the same distance.

Are you talking about pumice?

Well take a weight and make it orbit on a string. There is a force in the string called the centripetal force but the mass does not move in the direction of the force. This is because the centripedal force equals the centrifugal force.

It is something called the centrifugal force but this is still a fictitious force. http://en.wikipedia.org/wiki/Fictitious_force

That reduction in the normal force is called the centrifugal force.

if you collapsed and blocked the drainage the shower tray could fill enough to drown you. By the time someone finds you the water may have seeped away.

But if the only centripetal force is caused by gravity, the gravity will not change with speed of rotation but the normal force will.