Final answer:
The acceleration of the center of mass in a two-particle system, where one particle is at rest and the other has an acceleration a, is half the acceleration of the moving particle, or a/2.
Step-by-step explanation:
The acceleration of the center of mass for a system of two identical particles, where one is at rest and the other has an acceleration, is 1/2 the acceleration of the moving particle. When considering the center of mass, it represents a point where the system's mass is evenly distributed. If one particle is accelerating and the other is stationary, the acceleration of the center of mass is the average acceleration of the two particles.
Since one particle is at rest (acceleration of 0) and the other has a certain acceleration a, the center of mass will have an acceleration of (0 + a) / 2, which simplifies to a/2 or 1/2 the acceleration of the moving particle.