A pulley and a wedge questions.

[MathematicalPhysicist]

from the attachment, i need to answer question 2.15c and 2.16.

here is what i did with the questions:

in the first question i got the next set of equations, which apparently are incorrect cause i didnt get the answer from the book:
T-uM1g=M1a
uM2g-T=M2a
M3g-T'=M3a'
T'=2T
2a'=a
wher a' is the acceleration of mass M3 and a is of the other two, T' is the tension on M3 and T is the tension on the other two.

for the second question i got the next set of equations, which is also incorrect cause they for accelration with the respect to the y direction:
Nsin45=mg
mA+Ncos45=ma

thanks in advance.

 

[Doc Al]

You forgot the attachment.