Question

Assertion : A particle is moving on a straight line with a uniform velocity, its angular momentum is always zero.
Reason : The momentum is zero when particle moves with a uniform velocity

• A. If both Assertion and Reason are correct and the Reason is a correct explanation of the Assertion.
• B. If both Assertion and Reason are correct but Reason is not a correct explanation of the Assertion.
• C. If the Assertion is correct but Reason is incorrect.
• D. If the Assertion is incorrect and Reason is correct.

Answer 1

Answer: (D)

When particle moves with constant velocity $\vec{v}$ then its linear momentum has some finite value $(\vec{P}=m\vec{v})$. Angular momentum $(L)=$ Linear momentum $(P)\times$ Perpendicular distance of line of action of linear momentum form the point of rotation $(d)$ So if $d\ne 0$ then $L\ne 0$, but if $d=0$ then $L$ may be zero. So we can conclude that angular momentum of a particle moving with constant velocity is not always zero.