In one hand you hold a .12-kg apple, in the other hand a .20-kg orange. The apple
and orange are separated by .75 m. What is the magnitude of the force of gravity that
(a) the orange exerts on the apple?
(b) the apple exerts on the orange?



Answer :

AL2006
Forces of gravity between two masses = G M₁ M₂ / R²

G = universal gravitational constant =   6.67 x 10⁻¹¹  N-m² / kg²

F = (6.67 x 10⁻¹¹) (0.12) (0.20) / (0.75)²

F = 2.85 x 10⁻¹² Newton    (about  0.000 000 000 01 ounce)

The gravitational forces are always the same in both directions.
(Your weight on the Earth is the same as the Earth's weight on you.)