Explain
what is meant by a radian?
why is one complete revolution equivalent to an angular displacement of 
.
An elastic cord has an unextended length of 
. One end of the cord is attached to a fixed point C. A small mass of weight 
is hung from the free end of the cord. The cord extends to a length of 
, as shown in the figure below.
The cord and mass are now made to rotate at constant angular speed 
in a vertical plane about point C. When the cord is vertical and above C, its length is the unextended length of , as shown in the figure below.
Show that the angular speed of the cord and mass is 
.
made in one revolution is equal to the circumference 
of the circle made in one revolution.
