Which quantity in the gravity equation is a universal constant?

Which quantity in the gravity equation is a universal constant?

• A. The distance r
• B. The masses m1 and m2
• C. The exponent -2 on r
• D. The gravitational constant G

Answer: (D)

The key idea here is that Newton’s law of gravitation includes a single number that stays the same in every situation: the gravitational constant, G. It acts as the universal link between mass and gravity, so the force is proportional to the product of the two masses and inversely proportional to the square of their separation, but the proportionality factor G does not change from one system to another. The distance between the objects and the masses themselves can vary widely, causing the force to change, but G remains constant. The exponent -2 is part of the mathematical form that says how the force decreases with distance; it’s not a separate quantity that can vary. Therefore, the gravitational constant G is the universal constant. Its value is about 6.674×10^-11 N·m^2/kg^2, measured consistently across experiments.

The key idea here is that Newton’s law of gravitation includes a single number that stays the same in every situation: the gravitational constant, G. It acts as the universal link between mass and gravity, so the force is proportional to the product of the two masses and inversely proportional to the square of their separation, but the proportionality factor G does not change from one system to another. The distance between the objects and the masses themselves can vary widely, causing the force to change, but G remains constant. The exponent -2 is part of the mathematical form that says how the force decreases with distance; it’s not a separate quantity that can vary. Therefore, the gravitational constant G is the universal constant. Its value is about 6.674×10^-11 N·m^2/kg^2, measured consistently across experiments.