## Abhisar one year ago A man wishes to swim across a river 0.5 m wide. If he can swim at the rate of 2 Km/ h in still water and the river flows at the rate of 1 km/hr. The angle (wrt flow of water) along which he should swim so as to reach a point exactly opposite his starting point, should be?

1. imqwerty

really 0.5m wide river!!!

2. ChillOut

All right, let's draw that first.

3. Abhisar

Hahaha..nopes it should be 0.5 Km

4. imqwerty

lol ok :)

5. ChillOut

|dw:1437497187136:dw|

6. ChillOut

|dw:1437497254385:dw|

7. imqwerty

60 degrees

8. Abhisar

$$\color{blue}{\text{Originally Posted by}}$$ @imqwerty 30 degrees :) $$\color{blue}{\text{End of Quote}}$$ No direct answers and btw it's incorrect ...

9. ChillOut

The net horizontal velocity must be equal 0, so $$v*cos( θ )-1=0$$

10. ChillOut

Can you finish it, @imqwerty? :)

11. imqwerty

let the man make angle theta with the direction opposite to the river flow his horizontal component of velocity = Velocity of man x cos(theta) = Vcos(theta)=2cos(theta) this should equal the velocity of river flow so as to reach the directly opposite point so 2cos(theta)=1 cos(theta)=1/2 theta=60 degrees

12. Abhisar

It's incorrect...

13. Abhisar

|dw:1437497568545:dw|

14. Abhisar

The man should swim across the line AO and you have to find angle AOD

15. Abhisar

Ring a bell?

16. ChillOut

Oh, right. I didn't read the part where it states it's the angle between the flow and the man xD

17. Abhisar

Yes, so ?

18. ChillOut

So it means that the angle must be in the second quadrant, 120 degrees.

19. Abhisar

That's correct!