Question

A river has a steady speed of 0.480 m/s. a student swims upstream a distance of 1.00 km and swims back to the starting point. (a) if the student can swim at a speed of 1.40 m/s in still water, how long does the trip take?

Answer 1

Steady speed of river = 0.480 m/s

Swimming speed of student in still water = 1.40 m/s  

When the student is swimming upstream the  velocity he is going up = 1.40-0.48= 0.92 m/s

When the student is swimming downstream the  velocity he is going down = 1.40+0.48= 1.88 m/s

Time taken to travel upstream = $\frac{1000}{0.92} =1087 seconds = 18.12 minutes$

Time taken to travel downstream = $\frac{1000}{1.88} =592 seconds = 8.87 minutes$

Total time taken = 18.12+8.87 = 26.99 minutes