You are in a speedboat on a river moving in the same direction as the current. The speedometer on the boat shows that its speed is 20 km/h. However, a person on the shore measures the boat's speed as 23 km/h. How is this possible?
From the reference point of the river, the speed of the boat is 20 km/h. From the reference point of someone standing on the shore, the speed of the boat is the speed on the speedometer plus the downstream speed of the current.
