Two objects of equal mass are a fixed distance apart. If the mass of each object could be tripled, the gravitational force between the objects would ...

gravitational force between two objects is given as

F = G m₁ m₂/r²

where m₁ = mass of first object, m₂ = mass of second object, r = distance between the two objects.

Initial case:

m₁ = m₂ = m

gravitational force between the objects is given as

F = G m²/r²

Final Case:

m₁ = m₂ = 3 m

new gravitational force between the objects is given as

F' = G (3m) ²/r²

F' = 9 G m²/r²

F' = 9 F

hence the gravitational force between the two objects becomes 9 times.