Q 11-06-055JEE MainJEE Main 2026 (28 Jan, Shift 2)Easy
When the position vector $\vec r = x\hat i + y\hat j + z\hat k$ changes sign as $-\vec r$, which one of the following vector will not flip under sign change?
Answer: (D) Angular momentum
Under $\vec r\to -\vec r$: $\vec v = \dfrac{d\vec r}{dt}\to -\vec v$, $\vec p = m\vec v \to -\vec p$ and $\vec a \to -\vec a$ all flip.
Angular momentum $\vec L = \vec r\times\vec p \to (-\vec r)\times(-\vec p) = \vec r\times\vec p$, so it does **not** flip (it is an axial vector).
Solution by Sreeraj P, M.Sc Physics