A web page designer creates an animation in which a dot on a computer screen has position

r→=[4.0cm + (2.5cm/s^{2})t^{2}]ı^ + (5.0cm/s)t ȷ^.

a) Find the magnitude and direction of the dot’s average velocity between t = 0 and t = 2.0 s.

b) Find the magnitude and direction of the instantaneous velocity at t = 0, t = 1.0 s, and t = 2.0 s.

c) Sketch the dot’s trajectory from t = 0 to t = 2.0 s, and show the velocities calculated in part (b).