Laws of Motion#0

Acceleration of right block is $2 \text{ m/s}^2$ and that of left one is $3 \text{ m/s}^2$ . Then, in the frame of the right block, the acceleration of the left block is $5 \text{ m/s}^2$ .

In the frame of the right block, if the left block moves by x then the thread looses by 3x and the point P moves by 3x. Thus, if the acceleration of the left block is $5 \text{ m/s}^2$ , then, the acceleration of the point P will be 3 times 5 that is $15 \text{ m/s}^2$ .

Now, jumping back into the ground frame it will give $13 \text{ m/s}^2$ .