Question
A particle moves in a circle of radius r with constant angular velocity 
. What is the change in velocity when the particle describes an angle of 90°?
Solution
Let the particle revolve in circular orbit of radius r with constant angular velocity 
.
The speed of particle will be,
Let
be the velocity of particle at P and 
be the velocity of particle at Q after revolving by angle 
Therefore, angle between
is 
∴ Change in velocity
i.e.
. The speed of particle will be,
Let
be the velocity of particle at P and be the velocity of particle at Q after revolving by angle Therefore, angle between
is ∴ Change in velocity
i.e.
