1.

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

Answer» Correct Answer - C
`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)`.


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