What is the physical quantity represented by the unit $rpm$? Express it in $rad/s$.

$A$ body moves along a circular path of radius $15 \ cm$. It starts from a point on the circular path and reaches the end of the diameter in $3 \ s$. The angular speed of the body in $rad/s$ is

The angular speed of the minute hand of a clock in degrees per second is

For a particle executing uniform circular motion:

$A$ body is moving in a circular path with a constant speed. It has

Write the relation between linear speed and angular speed.