Single correct · +4 / −1
The SI units of the universal gravitational constant G are:
- (a) N·m
- (b) N·m²/kg²
- (c) N/kg
- (d) N/m²
Answer and solution
Answer (b) N·m²/kg²
Solution
Physics sir · 3 steps
Start from Newton's law of gravitation, make G the subject, and the units fall out on their own.
- Make G the subject. Newton's law says F = (G m₁ m₂)/r². Rearranging gives G = (F r²)/(m₁ m₂).
[G] = (N × m²)/(kg × kg) = N m² kg⁻²
- Check each piece. Force is in newtons, the distance is squared so it gives m², and two masses multiply to give kg² in the denominator.
- So. The SI unit of G is N m²/kg², which is option (b).
The idea to keep. To find the unit of any constant, write the law it appears in, make the constant the subject, and substitute the unit of every other quantity.
Answer from the NTA final answer key. Solution by PrepWiser.