Question

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) $ m{{v}^{2}} $
• D. the kinetic energy changes by $ m{{v}^{2}} $

Answer 1

Answer: (B)

Initial velocity
$ {{v}_{1}}=v $ Final velocity $ {{v}_{2}}=-\,v. $ Initial momentum $ {{p}_{1}}=mv $ Final momentum $ {{p}_{2}}=m\,(-v)=-\,mv $ Change in momentum $ \Delta p={{p}_{1}}-{{p}_{2}} $ $ =mv-(-mv) $ $ =2\,mv $