# Rotational Motion About a Fixed Axis , NEED HELp :\

1. 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 ?

## Answers and Replies

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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
Science Advisor
Homework Helper
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.

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