Question

A physical quantity which cannot be negative is

• A. Displacement
• B. Velocity
• C. Acceleration
• D. Distance

Answer 1

The correct option is D

Distance

Explanation for correct option

Option D: Distance

1. The actual length of the path travelled by a moving body irrespective of the direction is called the distance travelled by the body. It is a scalar quantity.
2. Distance is the path covered, the path covered has no particular direction and it can be covered in any way.
3. If some distance has been covered, it will always be measured in positive numbers.
4. Only distance cannot be negative because it never approaches zero. Since it is not a vector quantity, the direction has no impact on the sign.

Explanation for other options

Option A: Displacement

1. Displacement is the shortest distance between the initial position and the final position of the body, it is a vector quantity.
2. Displacement can be positive or negative depending on the reference point and it will be zero if the body comes back to its initial position.

Option $\mathrm{B}$: Velocity

1. The rate of change of position or displacement per unit time is called velocity, having unit as the meter/ second, but speed is scalar and velocity is a vector quantity.
2. Velocity can therefore be negative as long as it moves in a specified, negative direction.

Option C: Acceleration

1. The rate of change of velocity is known as acceleration and it is a vector quantity. It can be negative as long as it is in the direction opposite the motion.

The only parameter that cannot have a negative value is distance.

Hence, option $\mathrm{D}$ is the correct answer.