Quantcast Vacuum Sphere Text - Physics Forums Library

PDA

View Full Version : Vacuum Sphere


SPS
Jun19-08, 06:05 AM
Hi to you all,

May I just say I am not a physicist or the like so my questions may seem a bit green to you all, I wish to make something and need a little bit of info please.

With regards to a vacuum sphere, if I was to spin an item within it would it spin freely or would there be forces against it? Second silly question, does an item within the sphere become any lighter/heavier or no difference?

I hope the questions are worthy of a reply

Kind Regards

Steve

pantaz
Jun19-08, 07:23 AM
The vacuum will reduce aerodynamic drag, but that's all (assuming the sphere remains on Earth). You still have to deal with friction from the bearings supporting your spinning object.
A vacuum has no effect on gravity, so the relative weight of your object will not change.

SPS
Jun19-08, 09:05 AM
Thanks Pantaz for your reply, I am hoping i may be able to use opposing magnets to reduce the weight of my spinning object

Regards

Steve

pantaz
Jun19-08, 08:30 PM
Magnetic bearings will reduce (but not eliminate) friction. Weight will be unchanged.