Bicycle wheel, radius 90 cm.

The arrows represent the linear speed of 25 km/h

We learned that linear velocity for a wheel rotating at *ω* rad/s is given by:

*v* = *r* *ω*

The units are a mix of cm and km. Let's present everything in meters.

We need to convert *v* to m/s first.

`25\ "km/h" = 25000\ "m/h"`

` = 25000/3600 "m/s"`

` = 6.94444\ "m/s"`

Also, we have

`r = (90\ "cm")/2 = 45\ "cm" = 0.45\ "m"`

So `ω = v/r = 6.94444/0.45 = 15.43\ "rad/s"`

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