1 2 A drone flies in a straight line with a positive velocity v t in miles per hour at time t hours where v is a differentiable function of t Selected values of v t are shown in the table t hours 2 v t miles per hour 2 1 2 5 2 1 0 1 3 4 5 6 1 7 1 5 1 5 1 6 Based on the values in the table at is the smallest number of instances at which the acceleration of the plane could equal zero on the open interval 0 c 6 1 point