Why is speed classiﬁed as a scalar quantity and velocity classiﬁed as a vector quantity?
Speed has only magnitude and Velocity has both magnitude and direction.
By the definition of scalar quantity, they only have a magnitude and no definite direction.
Speed here does not have any specific direction and have only magnitude so is a scalar quantity.
Whereas Velocity is a vector quantity which can be specified both in the magnitude and direction.
Note similarities in characteristics below.
Scalar: magnitude but no direction.
Speed: magnitude but no direction. #" "Velocity: magnitude and direction.
I hope this helps,