일반물리학 1 — Force and Motion-I: Problem 56

56 In Fig. 5-41a, a constant horizontal force \(\vec{F}_a\) is applied to block A, which pushes against block B with a 15.0 N force directed horizontally to the right. In Fig. 5-41b, the same force \(\vec{F}_a\) is applied to block B; now block A pushes on block B with a 10.0 N force directed horizontally to the left. The blocks have a combined mass of 12.0 kg. What are the magnitudes of (a) their acceleration in Fig. 5-41a and (b) force \(\vec{F}_a\)?