if the net force on an object stays constant, what happens to the acceleration if the mass increases? explain your answer

The acceleration decreases if the mass increases, when the net force on an object remains constant.

Newton's Second Law

The acceleration of an object as produced by a net force is directly proportional to the magnitude of the net force, in the same direction as the net force, and inversely proportional to the mass of the object.

equation : F = m*a