In (the partial) solution, why does it consider the Tension,T, for finding the friction force between m1 and the surface? The tension is only affecting m1 in the horizontal direction. From where, the vertical component is apperaing?
What I want to ask is the (b) part (It's one of our old MTs). In the solution given, it talks about an acceleration,a3, on the horizontal axis. However, in the equation, the surface forces acting on m1 and m2, FN1 and FN2, are not affected by this acceleration, a3. Isn't that wrong?