45 rpm corresponds to 45 revolutions per minute.
In order to convert into rad/s, we should keep in mind that:
[tex]1 rev = 2 \pi rad[/tex]
[tex]1 min = 60 s[/tex]
so, the factor of conversion between rpm and rad/s is:
[tex]1 \frac{rev}{min} = \frac{2 \pi rad/rev}{60 s/min}=0.105 \frac{rad}{s} [/tex]
so, the angular speed converted in rad/s becomes:
[tex]\omega = 45 \frac{rev}{min} \cdot 0.105 =4.72 rad/s [/tex]
