In introductory mechanics, which statement best defines the impulse delivered to an object by a force over a time interval?

• A. The work done by the force, given by $W=\int F dx$.
• B. The average force during the interval, given by $F_{\mathrm{avg}}=\frac{\Delta p}{\Delta t}$.
• C. The object's momentum at an instant, given by $p=mv$.
• D. The change in momentum of the object, equal to $J=\int F dt$ (and for constant force $J=F\Delta t$).

Answer: (D)