Block 1 slides rightward on the floor toward an ideal spring attached to block 2, as shown. At time t1, block 1 reaches the spring and starts compressing it as block 2 also starts to slide to the right. At a later time, t2, block 11 loses contact with the spring. Both blocks slide with negligible friction. Taking rightward as positive, which pair of graphs could represent the acceleration of block 2 and the center-of-mass acceleration of the two-block system?
