Here's why:

* Newton's Second Law of Motion: This law states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

* F = m * a (Force = mass * acceleration)

* Equal Forces: If the forces are equal, the difference in acceleration is determined solely by the mass.

* Inverse Relationship: Since acceleration is inversely proportional to mass, a smaller mass will experience a larger acceleration for the same force.

In simple terms: Imagine pushing a small car and a large truck with the same amount of force. The small car will move much faster (accelerate more) than the large truck because it has less mass to overcome.