If the mass of an object increases but its acceleration remains constant, it means that a greater force is being applied to the object. According to Newton's second law of motion, the acceleration of an object is directly proportional to the force applied to it and inversely proportional to its mass. The formula for this relationship is F = ma, where F is the force, m is the mass, and a is the acceleration.
If the acceleration remains constant, it implies that the force acting on the object remains the same. However, if the mass increases, according to the equation F = ma, the force must increase proportionally to maintain the same acceleration. Therefore, the object requires a greater force to produce the same acceleration due to its increased mass.