The answer is 6 kg the mass of the second object. By using Inversely proportional formula it means that (14 kg) (3 m/s²) = M (7 m/s²). Where M is the mass of the second object. For the Newton’s second law of motion formula which is: Force = mass x acceleration, we have:
F = (14 kg) (3 m/s²) = 42 N
Therefore:
42 N = M (7 m/s²)
M = (42 N) / (7 m/s²)
M = 6 kg mass of the second object