Question

Eight charges each of value q each are placed on a ring of radius R placed in x-y plane with origin g at centre. –q charge having mass m is projected from z =  towards the centre of the ring with velocity v. The velocity of –q when it reaches the centre of ring is (neglect gravity)-

• A. $\sqrt{\frac{8kq^{2}}{mR}}$
• B. $\sqrt{\frac{8kq^{2}}{mR} + v}$
• C. $\sqrt{\frac{16kq^{2}}{mR} + v^{2}}$
• D. $\sqrt{\frac{16kq^{2}}{mR} + v}$

Answer 1

Answer: (C)

$\sqrt{\frac{16kq^{2}}{mR} + v^{2}}$

Answer 2

U_i + K_i = U_f + K_f

0 + $\frac { 1 } { 2 }$ mv² = mv'²

\ v' = $\sqrt { \frac { 16 \mathrm { kq } ^ { 2 } } { \mathrm { mR } } + \mathrm { v } ^ { 2 } }$