curves of its motion. 11.69 In a water-tank test involving the launching of a small model boat, the model's initial horizontal velocity is 6 m/s and its horizon- tal acceleration varies linearly from -12 m/s at t = 0 to -2 m/s at r = 1, and then remains equal to -2 m/s until t = 1.4 s. Knowing that v = 1.8 m/s when t = t, determine (a) the value of t, (b) the velocity and the position of the model at t = 1.4 s. Fig. P11.69 a (m/s)| vo = 6 m/s