Because of a storm, ground controllers instruct the pilot of a plane flying at an altitude of 4 miles to make a 90 turn and

Because of a storm, ground controllers instruct the pilot of a plane flying at an altitude of 4 miles to make a 90º turn and climb to an altitude of 4.2 miles. The model for the path of the plane during this maneuver is

where t is the time in hours and r is the distance in miles.

(a) Determine the speed of the plane.

(b) Calculate a_T and a_N. Why is one of these equal to 0?

r(t) = (10 cos 10 t, 10 sin 10mt, 4 + 4t), 0t2/0