Rotational Motion About a Fixed Axis , NEED HELp :\

[keylostman]

Homework Statement

A wheel of diameter of .68m roll without slipping. A point at the top of the wheel moves witha tangential speed of 5.4m/s. Whaat speed is the axle of the wheel moving? What is the angular speed of the wheel?

How would i approach to do this problem, what equations would i need to use ?

 

[keylostman]

ok for speed of axle i took .5 * 5.4 to get 2.7m/s

and for angular speed of wheel i took 5.4mn/s * .34m to get 15.9 rad/s

am i correct ?

 

[tiny-tim]

Hi keylostman!

Are you the same person as th3plan?

Why have you posted the same problem twice?

Your speed is right, but your angular speed is not.

Angular speed = speed/radius, where speed means speed relative to the centre.

You can either take the centre to be the axle - so the radius is .34, but you have to subtract the axle speed - or you can take the centre to be the (stationary) point of contact - so the radius is .68.

 

[keylostman]

so i take 5.4-2.7 ti get 2.7 m/s and multiply by .34m the radius to get .918 rad/s ?