The Petabyte of HDD's : A question about it

[Dunkan77]

Hello guys,

 

I just watched the video where Linus unboxes 100 HDD's and puts 60 in a single case. I wondered if the torque from the HDDs' initial spin up would affect how heavy it would feel should someone be holding the rack when the system boots.

 

I mean you can feel that little amount of torque with a portable HDD very easily: unplug it, hold it steady and plug it back in and you should feel a force which would be the opposite direction of the platters' rotation. Since they're all vertical, would they act a bit like in this video?: 

Or am I getting something mixed up but would it still be affecting the rack in any significant manner?

[DiamondShark286]

in theory the combined gyroscopic force of all the drives might make it  feels heavier or lighter but mainly probably just harder to rotate the case from side to side if it affects anything.

 

vsauce has a good video about gyroscopes if you want to get technical.

 

[Dunkan77]

3 minutes ago, Tb428 said:

 

in theory the combined gyroscopic force of all the drives might make it  feels heavier or lighter

 

Yeah that's exactly what I was thinking. Correct me if I'm wrong but I think it depends on the direction of spinning and their place relative to center of mass? Maybe not that last one but can you confirm it?

[DiamondShark286]

4 minutes ago, Dunkan77 said:

Yeah that's exactly what I was thinking. Correct me if I'm wrong but I think it depends on the direction of spinning and their place relative to center of mass? Maybe not that last one but can you confirm it?

if they all spin the same direction the resistance you would fell would be if you rotate side to side the force would be pull the drives to the center and forward or backward because you are changing the angle as the platters spin causing them to angle 90 degrees from where you apply force

[Dunkan77]

You mean like rolling motion? I guess it would make sense all the platters would try to keep their original axis of rotation so you'd feel a force preventing you from rolling the case side to side correct?

[ItsTheDuckAgain]

Captain here:

 

Of course, like always, you are all doing it wrong --> The more important question is: What happens when you put butter on a toast and tape it to a cats back and throw both out the window? 

 

Flying away

[Dunkan77]

2 minutes ago, ItsTheDuckAgain said:

Captain here:

 

Of course, like always, you are all doing it wrong --> The more important question is: What happens when you put butter on a toast and tape it to a cats back and throw both out the window? 

 

Flying away

Simple, the answer would be purple. Because aliens don't wear hats  

[DiamondShark286]

4 minutes ago, Dunkan77 said:

You mean like rolling motion? I guess it would make sense all the platters would try to keep their original axis of rotation so you'd feel a force preventing you from rolling the case side to side correct?

yes you should. the video i posted explains it better than i can but essentially if the the drives were sitting flat like in a normal and you pushed down on the side the drive would angle 90 degrees from where  applied pressure.  

[ItsTheDuckAgain]

1 minute ago, Dunkan77 said:

Simple, the answer would be purple. Because aliens don't wear hats  

that answer is correct!

you can leave work early today!

[DiamondShark286]

3 minutes ago, ItsTheDuckAgain said:

Captain here:

 

Of course, like always, you are all doing it wrong --> The more important question is: What happens when you put butter on a toast and tape it to a cats back and throw both out the window? 

 

Flying away

no infinite energy the cat tries to land on it feet while the toast always lands face down

[ItsTheDuckAgain]

2 minutes ago, Tb428 said:

no infinite energy the cat tries to land on it feet while the toast always lands face down

and then we turn the toast and repeat ....

 

voila: black hole generator !

[DiamondShark286]

1 minute ago, ItsTheDuckAgain said:

and then we turn the toast and repeat ....

actually both situations happen because quantum physics

[Dunkan77]

But on which side does the toast fall if you put butter on both?

[MajorGoob]

Would the platters have a significant enough mass to cause any noticable torque? They are Helium filled drives so that might make a difference on resistance or what the platter material is. I think an aluminum disk might have less torque production than a glass disk no?

[Dunkan77]

1 minute ago, Tb428 said:

actually both situations happen because quantum physics

Like schrodinger's cat  You planned it all along by starting with a cat! I call Illuminati

[DiamondShark286]

2 minutes ago, Dunkan77 said:

But on which side does the toast fall if you put butter on both?

both sides according to quantum physics the toast can do both #sSayNotToQuantumPhysics

[Dunkan77]

3 minutes ago, MajorGoob said:

Would the platters have a significant enough mass to cause any noticable torque? They are Helium filled drives so that might make a difference on resistance or what the platter material is. I think an aluminum disk might have less torque production than a glass disk no?

It depends on the platters' mass. I just googled it and aluminium has a slightly higher density than glass (2500 kg/m3 vs. 2700 kg/m3). So no aluminium disks would actually have more influence on the case. And for helium, it would just make the disks require less energy to be kept up to speed because it's less dense and therefore there's less friction acting on the platters

[DiamondShark286]

19 minutes ago, MajorGoob said:

Would the platters have a significant enough mass to cause any noticable torque? They are Helium filled drives so that might make a difference on resistance or what the platter material is. I think an aluminum disk might have less torque production than a glass disk no?

the helium  will not make a difference unless it causes the platters to spin faster which in this case is not what is happening because the force you feels is all through the axis that it rotates on and momentum not air density 

[DiamondShark286]

now I kind of want to make a gyroscope from  an old hdd running slower of course.

[MajorGoob]

12 hours ago, Tb428 said:

the helium  will not make a difference unless it causes the platters to spin faster which in this case is not what is happening because the force you feels is all through the axis that it rotates on and momentum not air density 

You are correct.... This is why I normally try and not think about any sort of anything before I actually wake up and get out of bed... I wrote that with my eyes half shut still. But yes, air density has no effect on centrifugal force, you are correct.