Impulse is defined as the product of the force applied to a body and the time interval for which that force acts: \(J = F \times \Delta t\).

By Newton's second law, force equals the rate of change of momentum, \(F = \dfrac{\Delta p}{\Delta t}\), so multiplying both sides by \(\Delta t\) shows that impulse equals the change in momentum, \(J = \Delta p\).

Momentum itself is mass times velocity, work is force times displacement, and power is the rate of doing work — none of these match force multiplied by time, which specifically defines impulse.