A particle B B\,B moves with constant acceleration (−4i−2j) ms−2(-4\mathbf{i} - 2\mathbf{j}) \text{ ms}^{-2}(−4i−2j) ms−2. At time t=0t = 0t=0, B B\,B has speed u ms−1u \text{ ms}^{-1}u ms−1. At time t=3 st = 3 \text{ s}t=3 s, B B\,B has velocity (−6i+2j) ms−1(-6\mathbf{i} + 2\mathbf{j}) \text{ ms}^{-1}(−6i+2j) ms−1.
Find the value of uuu.
