The 14 in. spring is compressed to an 8-in. length, where it is realeaed fomr rest and accelerate block A. The accerleration has an initial value of 400feet/sec^2 and then decreses linearly wiht the x-movement of the black, reacing zero when the spring regains its orinigal 14-in length. Calculate the time t for the block to go to 3 in.