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It is easy to show that adding energy to a rigid body can change the axis of rotation,

Quote from: Jaaanosik on 24/09/2020 18:51:25It is easy to show that adding energy to a rigid body can change the axis of rotation,Then show it.But no cheating.You have to do it without applying a torque.Only add energy.

Please, check this video: //www.youtube.com/watch?v=1VPfZ_XzisU

then there could be a cascade of events leading to big angular momentum changes.

The water moves to the walls the steam stays in the middle, close to the axis of rotation.

Then show it.But no cheating.You have to do it without applying a torque.Only add energy.

That leads to the angular velocity 'w (omega)' change because L=I*w and L is 'constant'.

Quote from: Jaaanosik on 24/09/2020 19:37:36That leads to the angular velocity 'w (omega)' change because L=I*w and L is 'constant'.You have accepted that L is constant, as part of your "proof" that L changes.Were you expecting to be taken seriously?

The angular velocity change is an angular acceleration change.

That leads to the axis of rotation change through the right hand rule.

You (Jano and gem) are seemingly claiming a change in momentum of these systems, which violates conservation laws. Energy input (without input of force or torque) has nothing to do with it, as BC and I repeatedly point out

However given the fact that occurs once the blades are in motion, we need to consider the initial frictional drag that occurs in the direction of the air flow, that then creates the lift to the turbine blades, and the subsequent force that the said drag applies to the tower and its foundations.Now given it is being argued that although there is torque the average net torque is zero to the system because, If the wind blows harder, it does so in all directions, or it pushes on something to move the other way.Also the wind blows/moves in cycles/cells so does not favour a net force/change in momentum in one direction.So in regards to what the mass of the air pushes against this is mostly the mass of other air especially when increasing momentum through the dynamics of changes in density occurring within the atmosphere, and as is well understood these changes in kinetic momentum are happening continually. (renewable) due to solar input to a fluid in a gravitational field creating the change/increase in kinetic momentum, through buoyancy effects.So consider the design of a anemometer which simultaneously rotates into and away from the wind of equal speed to both halfs in relation to itself, whilst still transferring momentum to favour one direction.https://en.m.wikipedia.org/wiki/AnemometerTherefore the coefficient of friction will/should come into consideration to different latitudes. given the established wind patterns, and the conditions as set out as per the OP

Quote from: gem on Yesterday at 00:39:51and the earth's atmosphere does not fulfil the criteria of conditions for energy or momentum conservationBCQuote I never said it did.

Due to frictional drag, therefore applying a force and torque to the solid of the earth's crust,

I believe all of the above are correct in regards to the conservation laws and its naive to argue for the atmosphere to fulfil the criteria of conservation of momentum when its clearly stated momentum can change due to the pressure gradient/buoyancy.indeed BC agrees

the momentum we observe as heat.which can ultimately be lost to the system via radiation to space.

You can't make energy into angular momentum.If you could it would break both conservation laws.

Quote from: Jaaanosik on 24/09/2020 19:37:36The angular velocity change is an angular acceleration change.That doesn't make sense.What do you mean?Quote from: Jaaanosik on 24/09/2020 19:37:36That leads to the axis of rotation change through the right hand rule.Not from my point of view., nor from that of, for example, an ant on the bean tin.If he sees the axis of rotation of his tin is lined up with a distant star then, even if the material inside melts + tumbles (like the water bottle in in the video) the axis of rotation will still point at the star.The rotation rate will also change but, if our clever ant calculates the moment of inertia of his bean tin world and multiplies it by the rate of rotation, he always get the same answer even though the axis of rotation changes (wrt the tin's axis)

If he sees the axis of rotation of his tin is lined up with a distant star then, even if the material inside melts + tumbles (like the water bottle in in the video) the axis of rotation will still point at the star.

Yes, the axis will be there but the angular velocity around this axis will be changing during the flip/transition.

Quote from: Jaaanosik on 25/09/2020 21:02:05Yes, the axis will be there but the angular velocity around this axis will be changing during the flip/transition.Yes it willAnd so will the moment of inertia; it will also change; in lock step with the rotation rate.But the product or the two, which is the angular momentum, will be constant.The angular momentum is a conserved quantity. The angular velocity and the moment of inertia are not conserved.Which is what the science has said all along.

How do boundary conditions work?

Quote from: Bored chemist on 24/09/2020 19:01:18Quote from: Jaaanosik on 24/09/2020 18:51:25It is easy to show that adding energy to a rigid body can change the axis of rotation,Then show it.But no cheating.You have to do it without applying a torque.Only add energy.

Quote from: Jaaanosik on 26/09/2020 18:02:19How do boundary conditions work?You draw a boundary round the relevant thing- in this case the tin, its contents and the ant. And say that's the system under considerationAnd then you measure the total angular momentum of the systemAnd you find it is constant.Quote from: Bored chemist on 26/09/2020 00:33:01Quote from: Bored chemist on 24/09/2020 19:01:18Quote from: Jaaanosik on 24/09/2020 18:51:25It is easy to show that adding energy to a rigid body can change the axis of rotation,Then show it.But no cheating.You have to do it without applying a torque.Only add energy.

Yes, I agree.But the point remains. The atmosphere may "borrow" angular momentum from the solid Earth (Though, even for a hurricane, the effect is tiny) but, the sum of their momenta is still the same as it was. And when the hurricane stops, it returns exactly the same angular momentum as it "borrowed.For the planet earth, as a whole, including the atmosphere, the angular momentum is constant.

Quote from: Bored chemist on 26/09/2020 19:39:48Quote from: Jaaanosik on 26/09/2020 18:02:19How do boundary conditions work?You draw a boundary round the relevant thing- in this case the tin, its contents and the ant. And say that's the system under considerationAnd then you measure the total angular momentum of the systemAnd you find it is constant.Quote from: Bored chemist on 26/09/2020 00:33:01Quote from: Bored chemist on 24/09/2020 19:01:18Quote from: Jaaanosik on 24/09/2020 18:51:25It is easy to show that adding energy to a rigid body can change the axis of rotation,Then show it.But no cheating.You have to do it without applying a torque.Only add energy.You cannot measure it with high enough precession therefore it is not going to be constant.

Quote from: Bored chemist on Yesterday at 00:33:01Quote from: Bored chemist on 24/09/2020 19:01:18Quote from: Jaaanosik on 24/09/2020 18:51:25It is easy to show that adding energy to a rigid body can change the axis of rotation,Then show it.But no cheating.You have to do it without applying a torque.Only add energy.

Now given the atmosphere does not fulfil the criteria for conservation of energy or momentum.

there appears to be a contradiction in this statement