Q. A 200-m-wide river flows due east at a uniform speed of 2.0 m/s. A boat with a speed of 8.0 m/s relative to the water leaves the south bank pointed in a direction 30° west of north. What are the (a) magnitude and (b) direction of the boat's velocity relative to the ground? (c) How long does the boat take to cross the river?

Q. A 170 g ball on a 60-{cm}-long string is swung in a vertical circle about a point 200 {cm} above the floor. The tension in the string when the ball is at the very bottom of the circle is 4.3 N. At the very bottom of the circle, a very sharp knife is suddenly inserted, to cut the string directly below the point of support. How far to the right of where the string was cut does the ball hit the floor?