External force and total momentum change for a system of objects (7-13)

Question 1 of 3

Question

Change during that time interval in the total momentum of the objects that make up the system

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Review

The quantity in parentheses on the left-hand side of Equation 7-12 is the sum of all of the $\textit{external forces}$ that act on the $\textit{system}$ of objects A and B. We’ll call this $\sum{\vec{F}_\mathrm{external\ on\ system}}$ for short. The right-hand side of the equation is the difference between the total momentum of the system after the time interval $\Delta{t}$ , $\vec{P}_f = \vec{p}_{Af} + \vec{p}_{Bf}$ , and the total momentum of the system before the time interval, $\vec{P}_i = \vec{p}_{Ai} + \vec{p}_{Bi}$ . So we can rewrite Equation 7-12 as: