To Find :

The force a exerted on object b

We can use Newton's law of universal gravitation:

F = [tex]\dfrac{G\times (m1\times m2)}{d^{2}}[/tex]

Here :

• F is the force in Newtons (N)
• G is the gravitational constant (6.674 × 10⁻¹¹ N⋅m²/kg²)
• m1 is the mass of object a in kilograms (kg)
• m2 is the mass of object b in kilograms (kg)
• d is the distance between the two objects in meters (m)

Putting in the given values we get:

F = [tex]\dfrac{6.674 × 10^{-11}\times (6\times 3)}{(6.7)^{2}}[/tex]

F = [tex]\dfrac{6.674 × 10^{-11}\times 18}{44.89}[/tex]

= 4.2 × 10⁻¹⁰ N

Therefore,

The force a exerted on object b is 4.2 × 10⁻¹⁰ N