Question

Two point masses $m$ and $2m$ are kept at points $A$ and $B$ as shown. $E$ represents magnitude of gravitational field strength and $V$ the : gravitational potential. As we move from $A$ to $B$

• A. E will first decrease then increases
• B. E will first increase then decrease
• C. V will first decrease then increase
• D. V will first increase then decrease

Answer 1

Answer: (A), (D)

The correct options are
A E will first decrease then increases
D V will first increase then decrease

E due to point mass is $E=\frac{Gm}{r^2}$
As $r\to 0$, $E\to \infty$
So, just over the point masses, $E=\infty$. Hence, in moving from one point mass to other point mass, E first decreases and then increases.
V due to a point mass is
$V=\frac{Gm}{r}$
As $r\to 0$, $V\to -\infty$
So, just over the point mass V is $-\infty$. Hence, in moving from one point mass to other point masss V first increases and then decreases.