Question

The vector product of two non-zero vectors is zero ______.

Options

• only when they are in the same direction.

• only when they are making angle 60°.

• only when they are perpendicular.

• when they are parallel or antiparallel.

Answer 1

The vector product of two non-zero vectors is zero when they are parallel or antiparallel.

Explanation:

The magnitude of the cross product is ∣\[\vec A\] × \[\vec B\]∣ = A B sin θ, which equals zero when θ = 0° (parallel) or θ = 180° (antiparallel), since sin ⁡0° = sin⁡ 180° = 0.