A person brings a mass of 1 kg from infinity to a point . Initally the mass was at rest but it moves at a speed of 2 `ms^-1` as it reaches A. The work done by the person on the mass is -3J. The potential at A is

Options

A. `-3 "J kg"^(-1)`
B. `-12 "J kg"^(-1)`
C. `-5 "J kg"^(-1)`
D. None of these

Answer

C

Explanation

`W=E_(A)-E_(infty)=(U_(A)+K_(A))-(U_(infty)+K_(infty))`
`:. -3={(1)V_(A)+(1)/(2)xx(1)(2)^(2)}-(0+0)" "(because W-3J)`
`:. V_(A)=-5"J kg"^(-1)`.