You use less energy to provide the same service.
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)
<em>F = 1.922 x 10⁻⁸ Newton</em> (about 0.0000000692 ounce of force)
5. between the stone and the ground
for a stone at rest on the ground, we have two forces acting on the stone. first is the force on the stone by the earth due to gravity of earth. second is the force applied by the ground in upward direction to balance the force of gravity on the stone.
so first interaction is between earth and stone : earth pulls stone towards it and stone pulls earth towards it by same amount of force.
second interaction is between stone and ground : ground push the stone in upward direction and stone push the ground in down direction by same amount of force.
hence the correct choice is
5. between the stone and the ground
A galaxy consist of billions of stars that contains gases and dust held together by gravity.
