A ball of mass `1g` and charge `10^(-8) C` moves from a point `A`. Where potential is `600` volt to the point `B` where potential is zero. Velocity of the ball at the point `B` is `20 cm//s`. The velocity of the ball at the point `A` will be

Options

A. 22.8 cm/s
B. 228 cm/s
C. 16.8 cm/s
D. 168 m/s

Answer

C

Explanation

`DeltaK = qV`
`implies 1/2 m(v_f^2 -v_i^2) =qV`
`implies1/2 xx1 xx10^(-3)[(0.2)^2-v_i^2]=10^(-8) xx600`
`implies 0.04 -v_i^(2) = 0.012 implies v_i^2 = 0.028`