ANSWER:
3rd option
Explanation:
First, let us consider block A:
By Newton's 2nd law of motion, force horizontal acting on the block A is given by F = m*a
As the block A and B, both are moving with constant velocity, the acceleration is zer .
Therefore:
F = m*a = 0
Then
uF = 0
There will be no horizontal force acting on block A
Now, considering block B:
Explanation:
First, let us consider block A:
Making the same analogy as in block A in block B, we have the following (F = uF):
Therefore, the correct option is the diagram of the 3rd option