Q. A particle is moving in a circle with uniform speed$v$. In moving from a point to another diametrically opposite point
A) the momentum changes by $mv$
B) the momentum changes by $2\ mv$
C) the kinetic energy changes by (1/2) $mv^{2}$
D) the kinetic energy changes by $mv^{2}$
Explanation
(b) Initial velocity
$v_{1} = v$
$Final\ velocity\ \ \ v_{2} = - v$
$Initial\ momentum\ p_{1} = mv$
$Final\ momentum\ \ p_{1} = m( - v) = - mv$
$Change\ in\ momentum\ \mathrm{\Delta}p = p_{1} - p_{2}$
$= mv - ( - mv)$
$= 2mv$j
[image:4_image162.emf]
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.