Might somebody clarify please?

[Gill Simo]

A simple question I'm sure so maybe just an even more simple person having to ask it!

I have a horizontal axle A with a vertical beam sat centrally upon it...and the same again (B) 'cept the beam is not vertical, not at a right angle to the axle but slanted/angled to some other degree.
In terms of all the physics at play when considering weight/mass in motion around an axle...are these two arrangements the exact same or does the angling of the beam change things?
Thanks/Gill

[UbWe]

A simple question I'm sure so maybe just an even more simple person having to ask it!

I have a horizontal axle A with a vertical beam sat centrally upon it...and the same again (B) 'cept the beam is not vertical, not at a right angle to the axle but slanted/angled to some other degree.
In terms of all the physics at play when considering weight/mass in motion around an axle...are these two arrangements the exact same or does the angling of the beam change things?
Thanks/Gill

They'd be in the same balance because each beam counterbalances itself.

[Fletcher]

I have a horizontal axle A with a vertical beam sat centrally upon it...and the same again (B) 'cept the beam is not vertical, not at a right angle to the axle but slanted/angled to some other degree.

In terms of all the physics at play when considering weight/mass in motion around an axle...are these two arrangements the exact same or does the angling of the beam change things?

Thanks/Gill

Is this what you are imagining Gill ? .. a black horizontal "spoke" within a wheel - then a second red "spoke" secured at right angles to it (A) - both spokes are pinned to the background disk which has a central pivot .. in the case of B the red spoke is titled over at some angle other than at right angles to the horizontal black spoke ?

If so the mass distribution of the disks and spokes is evenly distributed around the central disk pivot/fulcrum .. i.e. there is mass distribution symmetry .. which means balance (i.e. no net torque is produced by the arrangement) ..

When many and various weights are pinned to either the spokes, or the disk, then their positioning and individual mass values biases the system COM (mass distribution) to be either symmetrical or non symmetrical ..

Or I have completely missed what you are getting at with your question ..

[mickegg]

I see a black horizontal axle.

When in rotation (ends of red rod coming in and out of the screen /page) I would
expect the angled beam in B to try to align to that in A.

The force involved would lead to a bending of the black axle if it was not stong enough to withstand it,
and/or a fracture of the joint attaching it to the axle.

If it bends I would expect the system to be out of dynamic balance as the COG moves and the rotating
system may well vibrate.

Regards

Mick

[Robinhood46]

The only thing i think the difference could have an influence on is the air resistance of the bars.

[eccentrically1]

Yes, the angle affects the moment of inertia.

[Gill Simo]

Thank you's for your efforts to assist.
I think most are perhaps not seeing the simplicity here...the last two comments appear to see it best.
Undoubtedly my fault....I'll try to simplify.

I have a regular wheel, a disc on an axle & I give it a shove around.
I then force/bend the disc so that it no longer sits perpendicular to its axle...and give it a shove.
Assuming the same shove, will all forces at play have remained the same regardless?

[eccentrically1]

The same shove will accelerate B more than A. B will have less inertia.

[Robinhood46]

If i understand correctly what you are saying, i don't see any difference other than the forces that will be in play structurally, because of the displacement from being aligned with the axle. The forces will increase the work on the bearing which will increase friction and accelerate the losses.

[Gill Simo]

Soooo....eccentrically1.

If I have an A, in receipt of an input of energy that results in a max terminal speed of x rpm...then tilting this A to a B will have zero effect in terms of acceleration as A is already at max velocity?
Nor will there be any change in that max velocity?
The only effect/difference to be achieved between A/B, when in motion, is one whereby A will take longer to come to rest than B?

[UbWe]

Thank you's for your efforts to assist.
I think most are perhaps not seeing the simplicity here...the last two comments appear to see it best.
Undoubtedly my fault....I'll try to simplify.

I have a regular wheel, a disc on an axle & I give it a shove around.
I then force/bend the disc so that it no longer sits perpendicular to its axle...and give it a shove.
Assuming the same shove, will all forces at play have remained the same regardless?

There's a difference between moment of inertia and angular momentum. If you have a disc, 1/2 of the mass will be inside a circle and 1/2 of the mass outside of the circle. Then how fast that circle spins will give momentum = mv. With the inner and outer areas, they have the same surface area/volume.
With the black circle, how fast that spins would determine the angular momentum of the disc. It is the same way with beams. Regardless of orientation to each other, the only thing that will change centripetal force/angular momentum is shifting a weight towards or away from the axis of rotation. That will cause the angular momentum of weight to change.

[eccentrically1]

Soooo....eccentrically1.

If I have an A, in receipt of an input of energy that results in a max terminal speed of x rpm...then tilting this A to a B will have zero effect in terms of acceleration as A is already at max velocity?
Nor will there be any change in that max velocity?
The only effect/difference to be achieved between A/B, when in motion, is one whereby A will take longer to come to rest than B?

I can't guess what the max velocity would be without more info. If the beam is tilted while it's spinning, then the MoI is reduced making the beam easier to spin so it will spin faster than the perpendicular beam.
Yes, A spins longer.

[agor95]

A simple question I'm sure so maybe just an even more simple person having to ask it!

I also have been asking myself simple questions.

The one I have been thinking about; Can a tumbling tetrahedron be used as a base frame to implement a PM device independent from gravity?

As to your thought experiment; Imagine a disc with most of the mass around the rim. Then positioning the disc slanted until the disc is aligned along the hub axis. These are the two extreme cases.

So the first is like a spinning top and the second is like a coin spinning on it's edge.

What are your expectations with regards these two cases?

Think about MoI, CF and air resistance.

Regards

[Gill Simo]

Agor95....As to your thought experiment re my thought experiment, may I just first ask if I've understood you correctly please?

As per the simple diagram...a disc perpendicular to its axle (a) that slants fully over until it's aligned along it's axle (b)....si?

I ask because if that is correct then I'm stumped for seeing, in motion, both a spinning top (a) & a coin spinning on it's edge (b)..?