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CBSE - XI Science - Physics - Motion in a Plane

mam i dont know how to do this.plz answer.

Asked by 31st December 2011, 11:48 AM
Answered by Expert


Here main thing is to note that the 1 one is trying to swim at an angle theta and reached directly at B. The 2 one try to swim straight and reach at C then he walk toB.
let the width of river =d=AB
and let BC=x.
let the time taken by first person to reach at B =t.
let the time traken by 2 person to reach at C= t1
and to reach from Cto B=t2
so t=t1+t2--------(1)
For the first person-----
from the figure--------
U COS(?)=d/t----(2)
U sin(?)=2
means cos (?)=(?2.25)/2----(3)
from (2) and (3)
For the 2one--------
( because for the 2 one the the drift perpendicular to the river is only due to his own velocity 2.5, as the river velocity is perpendicular to his velocity)
( because the displacement of the 2 one along the river is only due to the river velovity as , his velocity is perpendicular to the river velocity)
from (5) and(6)
now he cover some distance by walking
from 1, 4, 5 and 8
solve above expresiuon and find v.
Answered by Expert 13th January 2012, 5:05 PM

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