Question

Which of the following is a scalar physical quantity?

• A. velocity
• B. average speed
• C. force
• D. displacement

Answer 1

The correct option is B

average speed

Explanation for correct option:

Option(B)

Scalar quantity:

1. Scalar quantities are those quantities that have only magnitude.
2. These quantities do not need any directions.
3. Ex: speed, distance, time, etc
4. Average speed is defined as the ratio of total distance traveled to total time taken.
5. Average speed does not require any direction.

Explanation for Incorrect options:

Option(A): Velocity:

1. Displacement per unit time is known as velocity.
2. S.I. unit of velocity is $m/s$
3. It is a vector quantity.

Option(C): force:

1. Force is required to change the velocity of an object or to change the direction of motion.
2. Its S.I. unit is $newton.$
3. It is a vector quantity.

Option(D): displacement:

1. It is the shortest path between the initial point and final point of the object.
2. S.I. unit of displacement is $m.$
3. It is also a vector quantity.

Hence, the average speed is a scalar quantity. Option B is correct.