Question

Two bodies of masses $2kg$ & $1.8kg$ are separated by $20m$ .
The distance of neutral point from smaller mass is :

• A. $10m$
• B. $5m$
• C. $3m$
• D. None of them

Answer 1

Answer: (A)

$10m$

Let the distance of neutral point from smaller mass be $R$, then

$\frac{G{m}_1}{R^2}=\frac{G{m}_2}{{\left(20-R\right)}^2}$

$\frac{R^2}{{\left(20-R\right)}^2}=\frac{m_1}{m_2}$

$\frac{R^2}{{\left(20-R\right)}^2}=\frac{1.8}{2}$

$\frac{R^2}{{\left(20-R\right)}^2}=\frac{9}{10}$

$\frac{R^2}{(20-R{)}^2}=0.9$

$\frac{R}{20-R}=0.95$

$1.95R=20$

$R=\frac{19}{1.95}$

$R=10m$