A trout jumps, producing waves on the surface of a 0.8-mdeep mountain stream. If it is observed that the waves do not travel upstream, what is the minimum velocity of the current?

The value is

Explanation:

From the question we are told that  

     The depth of the mountain is  

Generally the  velocity of the surface  wave  is mathematically represented as

=>          

=>      

Generally using the Froude number is mathematically represented as

Here V is the velocity of the current

 Given that  the waves do not travel upstream, then the flow of the current is  supercritical which means that

=>        

=>        

Hence the minimum velocity of the current  is  

This because the velocity of the  current is greater velocity of the surface  wave , so minimum will be like the lowest possible value of  V  which is v