If 𝑎 ⃗ > 0, Eq. 13 is negative. It means that A gains a force from B in the A→B direction rather than loses force. Simultaneously, for B, 𝑎 ⃗ < 0, Eq. 14 is negative, too. It indicates that B doesn't accept any force from A; instead, B loses a force in the A→B direction. Similarly, defining B's lost force as a force with the A←B direction, its quantity equals the force that A gains from B with the A→B direction. Colloquially, B pulls A (attraction). Therefore, A→←B is mutual attraction (Fig. ).