2 A car moves in a straight line with initial speed \(u \mathrm {~m} \mathrm {~s} ^ { - 1 }\) and constant acceleration \(a \mathrm {~m} \mathrm {~s} ^ { - 2 }\). The car takes 5 s to travel the first 80 m and it takes 8 s to travel the first 160 m . Find \(a\) and \(u\).