What is the magnitude of the gravitational force between the earth and a 1 kg object on its surface? (Mass of the earth is 6 × 10^24 kg and radius of the earth is 6.4 × 10^6 m)

Mass of Earth (M) = 6 × 10²⁴ kg

Mass of object (m) = 1 kg

Universal gravitational constant (G) = 6.7 × 10⁻¹¹ Nm² kg⁻²

Since the object is on the surface of the Earth,

r = radius of the Earth (R)

r = R = 6.4 × 10⁶ m

Therefore, the gravitational force

F = {GMm \over R^2}

= {6.7 × 10^{−11} × 6 × 10^{24} × 1 \over (6.4 × 10^6)^2}

= 9.8 N