Abhisar
  • Abhisar
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?
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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jamiebookeater
  • jamiebookeater
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Abhisar
  • Abhisar
Nuu..
Abhisar
  • Abhisar
|dw:1437500992112:dw|
Abhisar
  • Abhisar
|dw:1437501550342:dw|

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More answers

Abhisar
  • Abhisar
Time taken to cross the river = 0.5/2 = 1/4 Now in the same time the boat will travel a horizontal distance of AB. So AB = 1/4 * speed of river water = 0.25 Km Now, AB/BO = tan
Abhisar
  • Abhisar
So the answer should be tan -1
paki
  • paki
From where you got these angles...?
Abhisar
  • Abhisar
Which angle?
Abhisar
  • Abhisar
|dw:1437501819590:dw|
anonymous
  • anonymous
You were typing from the morning and you wrote from where you got those angles? @paki :P
paki
  • paki
lml... lag for me... sorry... :/
Abhisar
  • Abhisar
Are you guys able to spot the mistake?
paki
  • paki
|dw:1437501941480:dw|
anonymous
  • anonymous
From where you have taken boat in between this question? You got it for free?
Abhisar
  • Abhisar
@paki the question want us to find the angle with respect to flow of water along which the boat should go. @waterineyes the boat is goingg along the line OA
anonymous
  • anonymous
Wait, the man is swimming or he is in the boat??
Abhisar
  • Abhisar
lol, whatever :D I forgot..he is swimming
anonymous
  • anonymous
See, his speed of swimming is 2 km/h, and that of river is 1 km/h, he has to swim against the flow, so you need to find relative speed no?
anonymous
  • anonymous
Or relative velocity.. I mean, why you divide that by 2, where is the river speed then?
Abhisar
  • Abhisar
Ummm..not really. Read ex 1 of boat problems here http://www.physicsclassroom.com/class/vectors/Lesson-1/Relative-Velocity-and-Riverboat-Problems
paki
  • paki
Pythagorean theorem
anonymous
  • anonymous
Okay, I understood, that he will swim regardless or water current, and with his own speed, he will reach to point A..
Abhisar
  • Abhisar
Yes
anonymous
  • anonymous
*reach point A..
anonymous
  • anonymous
You have to find resultant velocity buddy..
anonymous
  • anonymous
Give me some time..
Abhisar
  • Abhisar
ok..
anonymous
  • anonymous
Okay...
anonymous
  • anonymous
See, the man has to swim straight, but river flow will make him flow as hypotenuse direction..
Abhisar
  • Abhisar
The man wants to reach the exact opposite point so he should swim along the hypotenuse on purpose so that river flow will make him reach on the opp side along a straight line.
anonymous
  • anonymous
|dw:1437502730218:dw|
Abhisar
  • Abhisar
YEs, man should swim along OB...right?
anonymous
  • anonymous
Okay then I am misinterpreting the question, wait more then.. :P
anonymous
  • anonymous
If we move along OB, then river flow must be opposite to reach A. Scratch that diagram.. :)
anonymous
  • anonymous
|dw:1437502906907:dw|
anonymous
  • anonymous
Okay, let me now again try..
Abhisar
  • Abhisar
|dw:1437503017553:dw|
anonymous
  • anonymous
|dw:1437502994510:dw|
anonymous
  • anonymous
You can use Pythagoras theorem to find the unknown side... \[R = \sqrt{2^2 - 1^2 } = \sqrt{3} \quad km/hr\]
anonymous
  • anonymous
|dw:1437503162276:dw|
Abhisar
  • Abhisar
one min
Abhisar
  • Abhisar
YaY!!!
Abhisar
  • Abhisar
Done...... dhika chika dhinka chika
anonymous
  • anonymous
Aise hi hoga na, main to bas tukke jyada aur dimaag kam chala raha tha. :P
Abhisar
  • Abhisar
Pata nahi answer to aa gaya :D
anonymous
  • anonymous
I got its nerve.. See, you have to take river flow and man or boat flow as vectors, draw them on paper to know their directions, on its basis you will get whether to subtract them in squares or to add them. :)
anonymous
  • anonymous
Once you find the unknown, finding angle is just a-jiffy work..
Abhisar
  • Abhisar
Ahaann...I see but there must be another way, something like i was doing earlier. I will mess with it tomorrow. But thank you, cz of uh i can seep in peace now :)
Abhisar
  • Abhisar
*sleep
anonymous
  • anonymous
Don't forget to wake up.. :P
Abhisar
  • Abhisar
I wish I could :D

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