State whether speed is a scalar or a vector quantity. Give reason for your choice.

Question

Vedantu Content Team · Accepted Answer

Hint: To solve the given question first we will know the definition of the terms “scalar quantity” and “vector quantity” and then based on the definitions we will distinguish whether speed is a scalar quantity or a vector quantity.Complete step by step solution:Scalar quantities: The quantities which only require magnitude and no direction to describe them are known as scalar quantities.Vector quantities: The quantities which require both magnitude as well as direction to describe them are called vector quantities. Speed and velocity formula respectively are given as:$\text{Speed} = \dfrac{\text{Distance}}{\text{Time}}$.and$\text{Velocity} = \dfrac{\text{Displacement}}{\text{Time}}$We know what distance and displacement are distance is the actual length of the path covered. So when we take a path with a lot of turns and curves, then the total length we cover is called distance.Displacement is the difference between the initial and the final positions of the path travelled.Speed is a scalar quantity because it does not need a direction of motion, it only needs magnitude.  We can add speeds without considering the direction of motion. 50 km/hr moving east is the same as 50 km/hr when moving west.But while for velocity 50 km/hr in east and 50 km/hr in west are different, because it focuses on the final and initial positions of the object. The speedometer of vehicles just shows speed regardless of the direction of motion.Note: We should note that when a vector quantity is multiplied with a scalar quantity, the product obtained is a vector with the same direction but increased magnitude. Speed is a scalar quantity whereas velocity is a vector quantity.

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