32) This problem asks us to validate the answer choices and choose the best answer. We are told that the mass of blocks A and B and different. Blocks A and B hang over a frictionless pulley of negligible mass.
Choices A and B: Be careful and make sure not to get confused by the diagram. Just because mass A is lower in the diagram, that doesn't mean it is heavier. If they told us the direction the masses move, we could tell which mass is heavier. However, the diagram doesn't tell us this. Both of these choices are incorrect.
Choice C: If the blocks moved with a constant velocity, the net force would be 0.
Since the blocks have different masses, the net force will not be 0; therefore, the masses are accelerating. The blocks cannot move with constant velocity if they are accelerating, so choice C cannot be correct.
Choices D and E: These choices make statements about the acceleration of the masses. Both of the objects should have the same constant acceleration; this makes sense because both the blocks are accelerating and connected to the same string. It is important that they are connected to the same string because it means they are forced to move together. If we want further proof, we can take a look at the equation we came up with above.
Since m[A], m[B], g, and m[total] are all constants, this shows us that both masses have the same constant acceleration. Choice D is true, but choice E cannot be true.
Answer: D
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