Question

To a man walking due west with a speed of 4m/s, wind appears to blow from the north-east, when he increases his speed to 7m/o the wind appears to blow from the north. Find velocity of wind with respect to ground.

(1) 50

(3) 58

(2) 40

(4) 42​

Answer 1

let v m andv a be the velocity of man and air respectively

let v a =v 1

i +v 2j

case 1 : v m =−7i

vva =(v 1 +7)i +v 2j

since VVa is along south-east (i.e. from north-west)so v 1 +7=−v 2 …(1)

case 2:v m =−3 iiva =(v

1 +3) i +2j

therefore wind blow at 5kmphfrom tan −1 ( 43 ) east of north

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