Question

Traveling along a river, a man in a row boat loses his hat when he passes under a bridge, but he keeps going in the same direction. In 15 minutes, he realizes that he lost his hat, and rows his boat the other way until he is able to retrieve his hat 1 km away from the bridge. What is the speed of the river's current?

Answer 1

Answer: 1.1 m/s

Explanation:

Speed
`s` is a relation between the traveled distance
`d` and time
`t`:

`s=(d)/(t)`

In this sense, we are told the man traveled a distance
`d=1 km=1000 m` for a time
`t=15 min (60 s)/(1 min)=900 s` before realizing he lost his hat.

With this information we can calculate the speed of the river's current, since we have the bridge where the hat fell as a reference point:

`s=(1000 m)/(900 s)`

`s=1.1 m/s` This is the speed of the river's current