4 All rivers flow into the sea or lakes. 5 Metals like iron contract when they are cooled. 7 It's sometimes difficult to determine what the weather will be like during the day. 8 A lot of the world's energy comes from burning fossil fuels.
Now, determine the trip length by substituting u=10 into the formula L = 3*(10 - 2) = 3*8 = 24 miles. Answer. The motorboat speed in still water is equal to 10 miles per hour. The trip length is equal to 24 miles. Problem 4. Airplane flying into the wind and with the wind Airplane flies for 6 hours against the wind.