According to the problem, the acceleration of an object varies inversely with its mass when a constant force is applied. This can be expressed as:
a = k/m
where a is the acceleration, m is the mass, and k is the constant of proportionality.
We can use this equation to solve for k:
k = am
For the first object with mass 2 kg and acceleration 39 m/s^2:
k = am = (39 m/s^2)(2 kg) = 78 N
Now we can use this value of k to solve for the mass of the second object, which has an acceleration of 6 m/s^2:
k = am = (6 m/s^2)(m) = 6m
78 N = 6m
m = 78 N / 6 = 13 kg
Therefore, the mass of the second object is 13 kg.