A hockey puck Q Q\,Q slides across smooth ice with constant acceleration. At time t=0t = 0t=0, Q Q\,Q is moving in the direction (−8i+6j)(-8\mathbf{i} + 6\mathbf{j})(−8i+6j) with speed 20 ms-1. After 8 seconds, its velocity is (4i+18j) ms−1(4\mathbf{i} + 18\mathbf{j}) \text{ ms}^{-1}(4i+18j) ms−1.
Find the acceleration of QQQ.