The impulse J associated with a force F acting during the time interval from t = t1 to t = t2 is the definite integral of the force, with respect to time, over the interval. Thus J is the vector quantity given by
Suppose that F is the total force acting on a particle of mass m. From Newton’s second law of motion in the form F = (d/dt)(mv), it follows that the impulse J is equal to the change in the linear momentum of the particle.
If the force F is constant, then J = F(t2−t1). This can be stated as ‘impulse = force×time’.
The concept of impulse is relevant in problems involving collisions.
Impulse has the dimensions MLT−1, and the SI unit of measurement is the kilogram metre per second, abbreviated to kgms−1.