2) Let r(t) =< sin2t, 3t, cos2t >, −ñ ≤ t ≤ ñ a) Show that the velocity and acceleration vectors are always perpendicular. b) Is there any time t for which r(t) and the velocity vector are perpendicular. If so, find all such values of t.

An object slides along the inside of a vertical circular track and never loses contact with the track. As it slides upward it slows down, and as it slides downward it speeds up. It's not known whether it's moving clockwise or counterclockwise in the view shown. Match points A, B, C, and D with possible acceleration vectors at those points. Only one of the acceleration vectors shown is possible at each point. A с a B

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