Question:medium

Read each statement below carefully and state with reasons, if it is true or false:
(a) The magnitude of a vector is always a scalar.
(b) each component of a vector is always a scalar
(c) the total path length is always equal to the magnitude of the displacement vector of a particle.
(d) the average speed of a particle (defined as total path length divided by the time taken to cover the path) is either greater or equal to the magnitude of average velocity of the particle over the same interval of time,
(e) Three vectors not lying in a plane can never add up to give a null vector

Updated On: Jan 21, 2026
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Solution and Explanation

(a) The magnitude of a vector is always a scalar.

Answer: True.

The magnitude of a vector is just a number representing its size or length, with no direction attached. Since scalars are quantities having only magnitude and no direction, the magnitude of a vector is a scalar.

(b) Each component of a vector is always a scalar.

Answer: False.

Each component (e.g. \( A_x, A_y, A_z \)) is a scalar number, but when we talk of the component along an axis as a vector, it has both magnitude and direction (along that axis). So numerically the components are scalars, but the component vectors themselves are vectors; the statement is ambiguous and taken as false in this context.

(c) The total path length is always equal to the magnitude of the displacement vector of a particle.

Answer: False.

Displacement is the straight-line vector from initial to final position, whereas total path length is the actual distance travelled along the trajectory. For curved or zig-zag paths, path length > displacement; they are equal only if motion is along a straight line in one direction.

(d) The average speed of a particle (total path length divided by time) is either greater or equal to the magnitude of average velocity over the same time interval.

Answer: True.

Average speed uses total path length, while average velocity uses displacement, whose magnitude is ≤ path length. Dividing both by the same time gives average speed ≥ magnitude of average velocity, equality only for straight-line motion in one direction.

(e) Three vectors not lying in a plane can never add up to give a null vector.

Answer: True.

For three vectors to sum to zero, they must form the sides of a triangle head-to-tail, which is only possible if they lie in a single plane. If the three vectors are not coplanar, they cannot form a closed triangle, so their vector sum cannot be the null vector.

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