|
|
Post by Progenitor A on Sept 11, 2012 21:03:11 GMT 1
Because some energy has been imparted to the object by an electric drill! Another form of WORK is happening that is reducing the work which otherwise would have to be done by the unaided muscle power of the human being.  This is very accurate and inarguable. The question is what is the force vector imparted by the drill that lightens up? |
|
|
|
Post by marchesarosa on Sept 11, 2012 21:28:28 GMT 1
Oh, I don't know anything about that difficult stuff, nay! But I like to put my bit in (geddit?) occasionally.
|
|
|
|
Post by Progenitor A on Sept 12, 2012 6:40:43 GMT 1
Oh, I don't know anything about that difficult stuff, nay! But I like to put my bit in (geddit?) occasionally. Yup you put your spin on things at times! |
|
|
|
Post by marchesarosa on Sept 12, 2012 8:18:25 GMT 1
That's the human condition, isn't it?
|
|
|
|
Post by striker16 on Sept 12, 2012 8:28:29 GMT 1
Of course it's a force. How do you define force?
Because the weight isn't as strongly attracted to the earth's gravity when experiencing angular momentum. One force is opposing another, and this is what forces do - push and pull.
|
|
|
|
Post by striker16 on Sept 12, 2012 8:35:26 GMT 1
Because some energy has been imparted to the object by an electric drill! Another form of WORK is happening that is reducing the work which otherwise would have to be done by the unaided muscle power of the human being. That is correct. The force of the drill is transferred into the spinning wheel as angular momentum, which opposes the force of gravity. Gyroscopes maintain their orientation using the same principle but, obviously, they need some source of energy to power them, just like the wheel obtained power from the drill. |
|
|
|
Post by Progenitor A on Sept 12, 2012 9:23:38 GMT 1
The force of the drill is transferred into the spinning wheel as angular momentum,......... Self-evidently ........which opposes the force of gravity. Not so self-evidnet Does angular momentum always oppose gravity? Have you ever seen a spinning disc out of control? I have and it hit the ground with a much bigger bang than its mere weight would have caused. In that case the angular momentum was adding to the force of gravity, not opposing it I am afraid that nothing is explained so far |
|
|
|
Post by mrsonde on Sept 12, 2012 9:34:48 GMT 1
I would contest your contestation, sir! At what point is "the turning point" of a parabola? Long time since I have done this stuff, but ignoring drag air resistance, when a stone is thrown up and forward against gravity it will follow an arc that approximates to a parabola. The 'turning point' of this parabola is when dh/dt = 0, where h= height of the stone, t= time. In plain English, the 'turning point' is where it is neither going up nor going down and that is the point of zero weight. That's the bit I'd disagree with. It's rather the point at which the gravitational influence becomes greater than impetus upwards. At this point the stone doesn't just drop, nor does it float - it still has forward and upward momentum, just not enough to resist the downward pull of gravity (that is, it has weight!) |
|
|
|
Post by mrsonde on Sept 12, 2012 9:37:59 GMT 1
Because some energy has been imparted to the object by an electric drill! Another form of WORK is happening that is reducing the work which otherwise would have to be done by the unaided muscle power of the human being. But why is the wheel spinning - the result of the work done by the electric drill - resulting in it being easier to lift? You're saying that if this spinning wheel were simply left on the ground, suitably constrained on a set of scales say, its weight would measurably vary? |
|
|
|
Post by mrsonde on Sept 12, 2012 9:54:02 GMT 1
Of course it's a force. How do you define force? The force is the external influence that has given the mass its angular momentum in the first place. In this case, electromotive. In physics, there are generally held to be four forces, are there not? Angular momentum is supposed to be an instance of inertia undergoing curvilinear motion, that's all. It's a property of the body concerned. It's not supposed to exert any influence on anything extrinsic to it, as a force would do. Well - I'm willing to grant there must be a momentum opposing Earth's gravity. But where is this momentum upwards coming from? How is it described and therefore predicted in the angular momentum equations? That predicts a torque and a momentum in the direction of (aligned with) the shaft, which as you say resists reorientation. Thus if anything the wheel should be experienced as heavier - or at least, harder to move - when one changes the angle between the earth and the shaft. Have you ever used a power-wheel? They're rather good. You set an internal gyroscope in a little plastic ball spinning - moving it about then requires considerable effort because of its angular momentum, thus exercising your forearms, primarily. |
|
|
|
Post by mrsonde on Sept 12, 2012 10:02:55 GMT 1
Because some energy has been imparted to the object by an electric drill! Another form of WORK is happening that is reducing the work which otherwise would have to be done by the unaided muscle power of the human being. That is correct. The force of the drill is transferred into the spinning wheel as angular momentum, which opposes the force of gravity. How? Why? The momentum of the wheel is circular - every direction is equal. The cetrifugal force also radiates equally in every direction. There's a torque produced by the angular momentum when he moves the lever, but that's at right angles to the shaft and the force of gravity, which is why he describes a circle in the air. That's all the angular momentum equations say. Nothing about gravity, and nothing about a momentum upwards. No they don't. Nothing to do with gravity at all. A gyroscope works n the same way in outer space. |
|
|
|
Post by mrsonde on Sept 12, 2012 10:06:52 GMT 1
You're not saying that a gyroscope set spinning on a scale would measure less? Or a spinning top? Where is this resistance to gravity produced by angular momentum then?
|
|
|
|
Post by striker16 on Sept 12, 2012 10:08:51 GMT 1
We are not talking about a spinning disc out of control in this case. Once again, forces can push or pull. A cannonball fired from a cannon can either oppose the pull of gravity or add to it, depending on its linear direction.
|
|
|
|
Post by Progenitor A on Sept 12, 2012 10:23:14 GMT 1
We are not talking about a spinning disc out of control in this case. Once again, forces can push or pull. A cannonball fired from a cannon can either oppose the pull of gravity or add to it, depending on its linear direction. Indeed. Why in the example shown does it oppose gravity Would reversing the spin cause it to add to gravity? If it spins at rt angles to gravity, what happens? |
|
|
|
Post by striker16 on Sept 12, 2012 10:23:30 GMT 1
All you have to remember is that here we have two separate forces being considered - gravity and angular momentum. The net effect on the spinning wheel is the interplay of both these forces. The spinning wheel will continue to spin forever unless acted upon by another force, in this case gravity. Linear motion and angular momentum are interchangeable anyway, so what's your point?
|
|
