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Byju's Answer

Standard XII

Physics

Instantaneous Velocity

A, B, C, D ar...

Question

A, B, C, D are four trees, located at the vertices of a square. Wind blows from A to B with uniform speed. The ratio of times of flight of a bird from A to B and from B to A is 'n'. At what angle should the bird fly from the direction of wind flow, in order that it starts from A and reaches C.
answer is theta = sin-(4n/(1+n)squared)
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Solution

he velocity of the bird with respect to air depicts velocity of the bird with respect to wind. So v is velocity of bird with respect to wind and u is velocity of wind with respect to ground. So velocity of bird with respect to ground is velocity of bird with respect to wind + velocity of wind with respect to ground ie v+u in case A to B and v-u in case B to A.

V(bw)=Vb - Vw (relative velocity concept)
Vb= V(bw)+Vw

Vbw--> velocity of bird with respect to wind
Vb--> velocity of bird with respect to ground
Vw--> velocity of bird with respect to wind

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Q. about 7 hours ago ANSWERED
A, B, C, D are four trees, located at the vertices of a square. Wind blows from A to B with uniform speed. The ratio of times of flight of a bird from A to B and from B to A is 'n'. At what angle should the bird fly from the direction of wind flow, in order that it starts from A and reaches C.
answer is theta = sin-(4n/(1+n)squared)
i saw the answer first we assume the velocity of bird wrt air is v and then putting v as the magnitude of velocity of bird wrt wind but are they same then for finding the relation between n ,v &u ;v+u would be velocity of bird because v=velocity of bird -velocity of wind.

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