does the "speed" change in a uniform circular motion ........
if yes ??? i think it is scalar and change in direction wont make any change
Your question is not clear. Although, we are explaining you the concepts of both uniform circular motion and speed.
Speed is distance travelled per unit time. Speed does not give any information on the direction of the moving body. Speed is a scalar quantity Velocity is a vector quantity.
Example: A truck is moving at a "speed" of 70 km per hour. Describes speed of the truck.
The motion of the object along a circular path with a uniform speed is called uniform circular motion.
Example : The motion of the moon around the earth is uniform circular motion.
For uniform circular motion :