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check my solution, relative velocity

check my solution, relative velocity

by Sinjan Jana -
Number of replies: 1
the question is

A man can swim at a speed of 3kmph in stilll water. he wants to cross a 500 m wide river flowing at 2kmph. He keeps himself always at an angle of 1200 with the river flow.

a> Find the time taken to cross the river.

b> At what point on the opposite bank will he arrive?

My doubt occurs in the 2nd part of the question.
the answer of the second part is 96 m on the right side.
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here is my solution.

the time taken comes out to be 1/3\( \sqrt{3} \)

2nd part of the answer

step 1: diagram
(click here)

step 2: click

step 3 : diagram


step 4: the displacement along the direction of Vsg is


           speed * time



           = \( \sqrt{19} \) * (1/3\( \sqrt{3} \))



           =  0.83 km.



step 5:  click here



The answer of my solution is wrong.



Can anyone please tell me where I am going wrong?

 


 

 


In reply to Sinjan Jana

Re: check my solution, relative velocity

by Chandni Bhatia -
Sinjan,the first mistake that you have done is that the angle between Vsr and Vrg is not 600.Then to find the horizontal distance,we need to take the horizontal component of Vsg .The horizontal component of Vsg=VRG- VSRcos600=0.5kmph.So,the displacement =(0.5kmph)*[1/3(3)0.5]h=0.09633km.Also,please tell how do you post images ?