Question

If in a system the force of attraction between two point masses of $1 kg$ each situated $1 km$ apart is taken as a unit force and is called notwen (newton written in reverse order). If $G = 6.67 \times 10^{11} N-m^{2} kg^{-2}$ in $SI$ units, the relation of newton and notwen is:

• A. 1 notwen $= 6.67 \times 10^{11}$ newton
• B. 1 newton $= 6.67 \times 10^{17}$ newton
• C. 1 netwen $= 6.67 \times 10^{-17}$ newton
• D. 1 newton $= 6.67 \times 10^{12}$ newton

Answer 1

Answer: (C)

If two point masses each of masses $1 kg$ are separated a distance $1m$ they experience a force $6.67 \times 10^{11}$ newtons.
We know $F=G\frac{m_{1}m_{2}}{r^{2}}$
$1$ notwen $=6.67\times10^{-11}\times\frac{\left(1 kg\right)^{2}}{\left(1 km\right)^{2}}$
$=6.67\times10^{-11}\times10^{-6} \frac{\left(1 kg\right)^{2}}{\left(1 m\right)^{2}}$
$=6.67\times10^{-11}\times10^{-6} $ newtons
1 notwen $= 6.67 \times 10^{-17}$ newtons