- #1
judas_priest
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Homework Statement
Two blocks of equal masses are placed on a horizontal table as shown. The bottom block is then pulled with a slowly increasing horizontal force F. The coefficients of static friction for both surfaces are greater than zero and equal to each other.
Here are the options:
A ) The top block begins to move as soon as F reaches a certain minimum value; the bottom block would never move even as F increases further.
B) The top block begins to move as soon as F reaches a certain minimum value; the bottom block does not move at that instant but would begin to move as F increases further.
C) Both blocks begin to move simultaneously as F reaches a certain minimum value; as F increases further, the acceleration of the bottom block exceeds the acceleration of the top block.
D) The bottom block begins to move as soon as F reaches a certain minimum value; the top block would never move even as F increases further.
E) The bottom block begins to move as soon as F reaches a certain minimum value; the top block does not move at that instant but would begin to move as F increases further. Status: incorrect
F) Both blocks begin to move simultaneously as F reaches a certain minimum value; as F increases further, both blocks always have the same acceleration.
G) Both blocks begin to move simultaneously as F reaches a certain minimum value; as F increases further, the acceleration of the top block exceeds the acceleration of the bottom block.
The Attempt at a Solution
On drawing FBD, the bottom block has three forces i.e external force, friction between block and ground, and the reaction friction force of top block.
On drawing FBD for top block, there's only one force that is friction between the two blocks. I don't know how to proceed from here. Is there physics involved? I think it's more of a logic question.