Assume you have 2 bodies A on top of B. They're both accelerating upwards at 0.5 ms^-2. This is my logic for finding the force exerted on B by A (correct me if I'm wrong)
I was told that to find this, you the force of A on B. And by Newton's 3rd Law, the force of B on A would be the same. How is that true as the reaction force of A is specific to A, right? So how can B exert the same force? Why isn't the force on B by A just the weight of A, not the reaction?
The force of A on B is gravity plus $.5\frac{m}{sec^2}$. Since A and B are at rest relative to each other, they either exert no forces on each other or equal and opposite forces. Hence B's force on A must also be gravity plus $.5\frac{m}{sec^2}$. Why isn't the force of A on B just the weight of A? Think of the astronaut in the chair at liftoff.