Question

A person brings a mass $2kg$ from $A$ to $B$. The increase in kinetic energy of mass is $4J$ and work done by the person on the mass is $-10J$. The potential difference between $B$ and $A$ is .......J / kg

• A. 4
• B. 7
• C. -3
• D. -7

Answer 1

Answer: (D)

The potential energy is given as,
$<br/>\left(U_B-U_A\right)+\left(K_B-K_A\right)=W_{AB}<br/>$
$<br/>\left(U_B-U_A\right)+4=-10<br/>$
$<br/>\left(U_B-U_A\right)=-14J<br/>$
The potential difference is given as,
$<br/>\begin{array}{l}<br/>\left(V_B-V_A\right)=\frac{\left(U_B-U_A\right)}{m}\\ <br/>\left(V_B-V_A\right)=\frac{(-14)}{2}\\ <br/>\left(V_B-V_A\right)=-7J/kg<br/>\end{array}<br/>$
Thus, the gravitational potential difference between $B$ and $A$ is $-7J/kg$.