A 69.0-kg astronaut is floating in space, luckily he has his trusty 28.0-kg physics book. He throws his physics book and accelerates at 0.0130 m/s2 in the opposite direction. What is the magnitude of the acceleration of the physics book? Give your answer relative to an observer who is space walking and therefore does not accelerate with either the astronaut or the poor physics book. (in m/s2)