1. A marble rolls with a velocity of 10 mm/s [E] on a game board that is being pulled [60^o N of E] at 40.0 mm/s. What is the velocity of the marble relative to the floor?

2. An airplane flies with a velocity of 55.0 m/s [ 35^o N of W] with respect to the air (this is known as air speed). If the velocity of the airplane according to an observer on the ground is 40.0 m/s [53^o N of W], what was the wind velocity?

3. If you were trying to cross a river with the shortest possible time, would you aim your boat slightly upstream, directly across the river, or slightly downstream? Explain.