Rotating platform on top of another rotating platform

AI Thread Summary
The discussion revolves around calculating the accelerometer readings on a rotating platform setup, where Platform A is spun by a centrifuge and Platform B (a Lazy Susan) rotates on top of it. Participants clarify the definitions of centripetal and angular velocity, emphasizing that accelerations are vector quantities that can be added. The relationship between the axes of rotation for the two platforms is crucial, as it affects the calculations. To accurately estimate the accelerometer readings, one must consider the acceleration of Platform B relative to Platform A and account for the varying position of the Lazy Susan during its rotation. Understanding these dynamics is essential for obtaining correct accelerometer measurements.
The Don
Messages
11
Reaction score
1

Homework Statement


Have platform A that is being spun by a centrifuge with a radius R1 and centripetal velocity of w1. On top of platform A is a Lazy Susan (Platform B) that spins about a radius R2 with a centripetal velocity of w2. There are accelerometers placed on the the purple platform (see pic). Estimate what the accelerometer readings will be.

Homework Equations


a_c = R*w^2

The Attempt at a Solution


I'm thinking the accelerometers readings would be the centripetal acceleration. I'm able to get the centripetal acceleration of Platform A and Platform B separately however I'm not sure whether the accelerometers would read the addition of these a_c or not. Please help!

upload_2015-12-3_12-27-28.png
 
Physics news on Phys.org
Hi Don, :welcome:

You sure this is the right picture? Where is A? B? Rotation axes? accelerometer postions? And which (x, y, z?) acceleration do they ,measure ?
 
The relationship between the two axes of rotation is unclear. Are they the same? Parallel? Orthogonal?
 
Hi BvU,

Here is another picture showing the rotation Axis...Platform A is the gray box and Platform B is the blue platform in the pictures. R1 is the radius of the centrifuge's arm and R2 would be approximately the length/2 of Platform B.

upload_2015-12-3_13-14-58.png
 
BvU said:
Hi Don, :welcome:

You sure this is the right picture? Where is A? B? Rotation axes? accelerometer postions? And which (x, y, z?) acceleration do they ,measure ?
Sorry please see my latest post in the thread
 
haruspex said:
The relationship between the two axes of rotation is unclear. Are they the same? Parallel? Orthogonal?
Yes, sorry for that. Please see latest post on the thread
 
Ok. First you don't mean centripetal velocity. That would mean the same as radial velocity (if it means anything.). The term here is angular velocity.
Accelerations are vectors, so can be added. Find tha acceleration of the Lazy Susan relative to the main axis, then add the acceleration of the accelerometer relative to the Lazy Susan axis. That's nontrivial since the second varies as the Lazy Susan rotates around the main axis, so you need to include variables representing the instantaneous position of the LS.
 
Back
Top