Question

A particle of mass m is moving in horizontal circle of radius $r$ with uniform speed $v$. When it moves from one point to a diametrically opposite point its

• A. KE changes by $m{v}^2$.
• B. KE changes by $\frac{1}{4}m{v}^2$.
• C. momentum does not change.
• D. momentum changes by $2mv$.

Answer 1

The correct option is D momentum changes by $2mv$.

At diametrically opposite points velocity of particle is same but opposite in direction. Hence, change in momentum is
$p=mv-(-mv)=mv+mv=2mv$