Q1. A 0.20 {rm kg} rock is thrown vertically upward from the top of a cliff that is 31.0 {rm m} high. While it hits the ground at the base of the cliff, the rock has the speed of 31 {rm m/s}. Assume that air resistance can be ignored; find the initial speed of the rock.
Q2. A small motor boat is capable of maintaining a 9.00 m/s speed in still water. It attempts to cross a long straight 0.60 km wide river that has a constant 3.60 m/s current.