Question

A vector quantity is a physical quantity which needs

• A. magnitude
• B. direction
• C. both A and B
• D. time

Answer 1

The correct option is C

both A and B

The explanation for the correct option

C: both A and B

1. Vector quantities are physical quantities that are completely defined by the number of units or magnitude and the direction in which they are measured.
2. For example, knowing the speed with which a thrown ball is launched, is required in order to retrieve it. As a result, the magnitude of a vector quantity is required.
3. Now, in order to locate the ball more easily, it is required to know not only the speed with which it is thrown but also the direction in which it is launched. As a result, the direction of a vector quantity is required.

Hence, a vector quantity requires both magnitude and direction.

The explanation for incorrect options

A: magnitude

A vector quantity requires direction as well.

B: direction

A vector quantity requires magnitude as well.

D: time

In physics, we express those values as vectors with direction, where "direction" refers to a three-dimensional spatial direction. Time does not have a direction. Time is not a vector quantity for this reason. It requires only magnitude.

Hence, option C is the correct option.