Newton's laws homework: inclined plane with pulley

[akapm90]

Homework Statement

A wedge-shaped block of mass M is placed on a smooth plane inclined at an angle α to the horizontal. The block M has a vertical rectangular slot. Inside this slot, a smaller block of mass m is hanging connected to light, inextensible string, and passes over an ideal pulley fixed to block M, and fixed to the right-hand wall. Assume all surfaces are frictionless and the pulley and string are massless.

Calculate:
1- The magnitude of the the acceleration of block M
along the inclined plane.
2- The tension T in the string.

Relevant Equations

$$\sum F_{mx} = -F_i = ma_x$$
$$\sum F_{my} = T - mg = ma_y$$
$$\sum F_M = - Mg \times \sin \alpha + F_i \times \cos \alpha + T(\sin \alpha - \cos \alpha) = Ma_M$$
$$ a \times \cos \alpha = a_{mx}$$

I have this homework, I spend 3 days trying to solve it but I still don't get it.
The forces acting over M are the weight, the normal, the tension (up and down), and some internal force with mass m.
In m the weight, tension and some internal force with mass M.
Since there is a tension acting horizontally (at first) in M, it contributes to its acceleration. My question is; as M goes down, this tension won't be parallel to the ground anymore. Does this mean that acceleration is variable? Still if we assume that we want the acceleration at that instant, we still have the acceleration of m in the y-axis, and I can't relate this to the acceleration of M. With the acceleration of m in the x-axis we have that it's the same from M.

 

[TSny]

I'm wondering if the question is asking for the acceleration $a$ and tension $T$ as functions of time, or if it is asking only for the values of $a$ and $T$ immediately after the system is released (while the upper portion of the string is horizontal)?

 

[akapm90]

It doesn't specify after the system is released, I assume refers to that. But not in function of time, it asks for a specific formula of $$a_M$$ using $$M, m, \alpha$$

 

[TSny]

It doesn't specify after the system is released, I assume refers to that. But not in function of time, it asks for a specific formula of $$a_M$$ using $$M, m, \alpha$$

OK. I see now that you already brought up this ambiguity in your first post. Thanks.