1. The problem statement, all variables and given/known data A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff. 4.3 s later the stone hits the ground. What is the height of the cliff? A swimmer heading directly across a river 200 m wide reaches the opposite bank in 6 min 40 s. She is swept downstream 480 m. How fast can she swim in still water? 2. Relevant equations The problem here is that I don't understand why some equations are used sometimes... 3. The attempt at a solution For example, for the first question, I just calculated 43 meters, since the speed is 10 meters per second. I am aware that the speed accelerate continuously, but I don't understand which equation to use. For the second question, it's the same thing. I found 0.5 m/s. Thanks for explaining where I am not thinking correctly. I know that my answers are not correct (well, pretty sure)..