Question

Two-point masses each equal to $1$kg attract one another with a force of ${10}^{-10}N$. The distance between the two-point masses is $(G=6.6\times {10}^{-11}MKSunits)$

• A. $8cm$
• B. $0.8cm$
• C. $80cm$
• D. $0.08cm$

Answer 1

The correct option is C

$80cm$

Step $1$: According to newton's Gravitational Law,

$F_g=\frac{G{M}_1{M}_2}{r^2}\left(where{F}_g={10}^{-10}Newton\right)$

It is given that

$$\begin{gathered} M_1=M_2=1kg \\ G=6.6\times {10}^{-11}N{m}^{2}k{g}^{-2} \end{gathered}$$

Step $2$: Now using Step $1$,

$$\begin{gathered} r^2=\frac{G{M}_1{M}_2}{F_g} \\ =\frac{6.6\times {10}^{-11}\times 1\times 1}{{10}^{-10}} \\ =0.66 \end{gathered}$$
Step $4$: Let's find the value of $r$,

$$\begin{gathered} r=0.8125metre \\ =81.25cm \\ =80cm \end{gathered}$$

Hence, Option (c) $80cm$is the correct answer.