Respuesta :
Answer:
Option e) 320 s
Explanation:
Here, distance = 3.0 km = 3000 m
The velocity of boat when it is going upstream;
Upstream velocity = velocity of boat in still water - velocity of river flow
So, Upstream velocity [tex]=20m/s-5m/s=15m/s[/tex]
So,Time to go upstream
[tex](t_{1}) =\frac{Distance}{Velocity}=\frac{3000m}{15m/s} =200 s[/tex]
The velocity of boat when it is going downstream;
Downstream velocity = velocity of boat in still water + velocity of river flow
So, Downstream velocity [tex]=20m/s+5m/s=25m/s[/tex]
So,Time to go downstream
[tex](t_{2}) =\frac{Distance}{Velocity}=\frac{3000m}{25m/s} =120 s[/tex]
So, total time (t) = [tex]t_{1}+t_{2}=200s+120 s=320s[/tex]
Option E is the correct answer.
Answer:
Time required for round trip is 320 s.
Explanation:
Given :
Velocity of boat in still water , v = 20 m/s.
Velocity of river , V = 5 m/s.
In the given question boat make round trip to a town 3 km upstream.
Therefore, Total time = time taken in upstream + time taken in upstream.
We know , [tex]t=\dfrac{D}{v}[/tex] ( here all have their usual meaning ).
Total time , [tex]t=\dfrac{3000}{(20-5)}+\dfrac{3000}{(20+5)}[/tex] ( upstream velocity = 20-5 = 15 m/s.
downstream velocity = 20+5 = 25 m/s)
[tex]t=200+120=320\ s.[/tex]
Hence, this is the required solution.
