Question

A 60kg student is 5m from a 120kg door, how much gravitational forces act between the two?

Answer 1

Gravitational force = G · m₁ · m₂ / r²

' G ' is the 'universal gravitational constant, 6.673 x 10⁻¹¹ m³/kg-s²

m₁ = 60 kg

m₂ = 120 kg

r = 5 m

F = (6.673 x 10⁻¹¹ m³/kg-sec²) · (60 kg) · (120 kg) / (5m)²

F = (6.673 x 10⁻¹¹ · 60 · 120 / 25) · (m³ · kg · kg / kg · s² · m²)

F = 1.922 x 10⁻⁸ (kg · m / s²)

F = 1.922 x 10⁻⁸ Newton  (about 0.0000000692 ounce of force)