Linear acceleration and a grinding wheel

[MIA6]

Homework Statement

A grinding wheel 0.35 m in diameter rotates at 2500rmp. What is the linear acceleration of a point on the edge of the grinding wheel?
For the linear acceleration, should it be atotal=atan+aR? Should we find both tangential acceleration and centripetal acceleration? But on the answer key, it's only centripetal acceleration. i dont' know why? But also I can not find tangential acceleration since I don't know the time. Hope you can help. thanks.

 

[MIA6]

Should we find both tangential and centripetal acceleration?

 

[PhanthomJay]

Should we find both tangential and centripetal acceleration?

The wheel is rotating at constant angular velocity and constant tangential speed; ; therfore, it has no tangential acceleration, just radial (or centripetal) acceleration.

 

[MIA6]

How do you know it's constant angular velocity? Because it didn't say anything about acceleration of angular velocity?

 

[PhanthomJay]

How do you know it's constant angular velocity? Because it didn't say anything about acceleration of angular velocity?

It said it it is moving at 2500rpm. That is a constant angular velocity. If it was accelerating, it would have stated such, or at least made a veiled reference to it and given other data. It is like saying that a train is moving at 90mph...there is no reason to believe that the train is accelerating if it is not stated, that is, the 90 mph is assumed a constant speed.

 

[MIA6]

Ok. I got it. Thank you.