Answer:
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