Newton's second law basically states that the acceleration of a body which is produced by a net force is directly proportional to the magnitude of net force applied in the same direction.
This tells us that
F is directly proportional to a
⇒ F= ma
So we can also state from the above equation, that when we have more mass, we need more net force to accelerate it. Here, we are keeping the acceleration constant so we can surely say that force and mass varies directly.
Therefore, we have made good use of Newton's Second Law of motion to arrive at this conclusion.
