If mass does not change then acceleration of a particle is dependent on the forces acting upon the particle and the particle's mass. For a given particle, if the net force is increased, the acceleration is increased. For a given net force, the more mass a particle has, the less acceleration it has.
hence the rate of change of momentum of a body is directly proportional to the applied force
A resultant force causes acceleration and a change in the velocity of the body for as long as it acts.The change in momentum is equal to the product of the average force and duration. Conversely, a small force applied for a long time produces the same change in momentum, the same impulse, as a larger force applied for a short time interval.
Impulse J is
The impulse is the integral of the resultant force (F) with respect to time