For the remainder of the question, you should you use this value of T.
Block B is now cut at an angle of 30° to the horizontal into two smaller blocks. The upper block has a mass of 4 kg, and the lower block has a mass of 6 kg. The two blocks are held at rest with the lower block on Π. The horizontal force of magnitude T N is now applied to the lower block (see Fig. 2).
The two blocks are released from rest and in the subsequent motion the upper block starts to move with acceleration 3.5 m s-2.
Determine the coefficient of friction between the two blocks.