Question

A particle of mass $M$ is moving in a horizontal circle of radius $R$ with uniform speed $v$. When the particle moves from one point to a dramatically opposite point, its

• A. Momentum does not change
• B. Momentum changes by $2Mv$
• C. Kinetic energy changes by $\frac{M{v}^2}{4}$
• D. Kinetic energy changes by $M{v}^2$

Answer 1

The correct option is B Momentum changes by $2Mv$

Velocity of the particle at one point and at diametrical opposite point in $v$ and $-v$, respectively.
Change in momentum $\Delta P=P_f-P_i$ $=Mv-(-Mv)$
$\Delta P=2Mv$