Question 450461
Inversely proportional means that


(9 kg)(5 m/s^2) = M(3 m/s^2)


where M is the mass of the second object. Solving, we get M = 15 kg.




Or, if you know Newton's second law (Force = mass*acceleration) we have


F = (9 kg)(5 m/s^2) = 45 N = M(3 m/s^2). Here, we also obtain M = 15 kg.