Speed of rotor tip with 7.6m diameter at 450 rev/min

[john_halcomb]

have a question.
diameter of a rotor is 7.60m and rotational speed of 450 rev/min. calculate speed of tip. anywell would be welcomed

 

[Pyrrhus]

What equation relates both?

$$v = \omega r$$

 

[john_halcomb]

the answer in the back of the book says179 m/s. but when i try that formula it comes out as 311.6

 

[Pyrrhus]

Oh sorry, yes the book is right

A rev is equal to 2 pi radians, and a minute is equal to 60 second. You need to homogenize (spl?) your units.

 

[john_halcomb]

the rev/min is 47.81 rev/sec

 

[john_halcomb]

sorry its 47.12 rad/s

 

[Pyrrhus]

Multiply it with 3.8 m