If the mass of planet Earth doubled, how would the force of gravity between Earth and the Sun change?

The force of gravity would double
The force of gravity would increase four times
The force of gravity would not change
the force of gravity would decrease by half

1 answer

The force of gravity between two objects is described by Newton's law of universal gravitation, which states:

\[ F = G \frac{m_1 m_2}{r^2} \]

where:

  • \( F \) is the gravitational force,
  • \( G \) is the gravitational constant,
  • \( m_1 \) and \( m_2 \) are the masses of the two objects, and
  • \( r \) is the distance between the centers of the two objects.

If the mass of the Earth (let's say \( m_1 \)) doubles, the new mass becomes \( 2m_1 \). The mass of the Sun (let's say \( m_2 \)) remains the same, and the distance \( r \) does not change.

Plugging this into the equation, the new gravitational force (\( F' \)) would be:

\[ F' = G \frac{(2m_1) m_2}{r^2} = 2 \left( G \frac{m_1 m_2}{r^2} \right) = 2F \]

This means the force of gravity between Earth and the Sun would indeed double.

Therefore, the correct answer is:

The force of gravity would double.