A moderate wind accelerates a pebble over a horizontal xy plane with a constant acceleration a = (5.00 m/s2)i + (7.00m/s2)j. At time t = 0, the velocity is (4.00m/s)i. What are the
(a) Magnitude and
(b) Angle of its velocity when it has been displaced by 12.0 m parallel to the x axis?