What is the differnce between convex and concave lens

An object starts from rest at point f and speeds up continuously as it moves around an oval. a. choose a point about 1/8 th of the way around the oval from point f, and label it point g. draw a vector to represent the velocity of the object at point g. b. determine the change in velocity vector   between points f and g.

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If the force applied to an object remains constant, is more power needed for the object to move faster ? explain