Wind is blowing at a speed of 70 km/hr and the flag hoisted on a ship in a harbour flutters along N-E direction.if the ship starts moving at a speed of 50 km/hr towards north,what will be the direction of the flag hoisted on the ship?

Asked by  | 14th Jun, 2013, 07:00: PM

Expert Answer:

speed of wind = 70 kmph in NE dir
 
speed of ship = 50 kmph in north dir
 
angle between the two  = 45 degree
thus the flag will now flutter in the direction of their net velocity
thus using parallelogram law of addition of velocities,
 
net V2 = 502 + 702 + 2.50.70.cos(45)
and V = 111.12 kmph
and direction = tan-1[70.cos(45)/(70.sin(45)-50)]
(It can be easily derieved using vector resolution and general use of trigonometry)

Answered by  | 14th Jun, 2013, 10:34: PM

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