Which of the following is not a vector quantity?

Why Speed is not a Vector Quantity?

Speed is a scalar quantity. It has only magnitude and no direction. The scalar quantity is measured by a single integer and an appropriate unit. Examples of scalar quantity are Volume, Mass, electric current, distance, density, time, etc.

The term "vector quantity" or "vector" is a physical quantity which has magnitude as well as direction. A number with a unit and its direction are used to represent a vector quantity. Examples of vector quantity are velocity, force, momentum, acceleration, etc.

Summary:

Which of the following is not a vector quantity? (a) speed (b) velocity (c) displacement (d) acceleration

Speed is not a vector quantity. Speed is the rate at which the object moves along a certain path. It has only magnitude hence it is a scalar quantity whereas a vector quantity has both direction and magnitude.