The amount of the gravitational force doubles.
According to Newton's law of universal gravitation, the gravitational force \( F \) between two objects is directly proportional to the product of their masses \( m_1 \) and \( m_2 \), and inversely proportional to the square of the distance \( r \) between their centers. The formula is:
\[ F = G \frac{m_1 m_2}{r^2} \]
Where \( G \) is the gravitational constant. If the mass of one object doubles (let's say it changes from \( m_1 \) to \( 2m_1 \)), while the other mass \( m_2 \) and the distance \( r \) remain unchanged, the new gravitational force becomes:
\[ F' = G \frac{(2m_1) m_2}{r^2} = 2(G \frac{m_1 m_2}{r^2}) = 2F \]
So, the gravitational force doubles.