𝐹 = 𝑚 𝑎 ⃗ (14) However, it should be noted that, for A, dL>0, but for B, dL<0, thus 𝑎 ⃗ > 0. B certifies that B accepts a positive force from A. As a result, B is about to move along with the A→B direction. Colloquially, A pushes B (Fig. ).