The universal gravitational constant $G$ has the SI value approximately:
A$6.67 \times 10^{-11}\,\mathrm{N\,m^2/kg^2}$
B$9.81\,\mathrm{m/s^2}$
C$6.022 \times 10^{23}\,\mathrm{/mol}$
D$1.6 \times 10^{-19}\,\mathrm{C}$
Answer & Solution
Correct answer: A. $6.67 \times 10^{-11}\,\mathrm{N\,m^2/kg^2}$
Universal gravitational constant $G = 6.67 \times 10^{-11}$ N·m²/kg² in SI units, the same everywhere in the universe.
The units come from Newton's law $F = G m_1 m_2 / r^2$: $\dfrac{\text{kg} \cdot \text{kg}}{\text{m}^2} \cdot [G] = \text{N}$, so $[G] = \text{N} \cdot \text{m}^2 / \text{kg}^2$.
Option B is the local acceleration due to gravity $g$ (not constant). Option C is Avogadro. Option D is the electronic charge.
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