In a harbour, wind is blowing at the speed of 72 km/h and a flag on the mast of a boat anchored in the harbour flutters along the N-E direction. If the boat starts moving at a speed of 51 km/h to the north, what is the direction of the flag on the mast of the boat?
Let east be taken along X-axis and north along Y-axis.
Velocity of wind is,
Velocity of boat,
The flag flutters in the direction of relative velocity of wind relative to boat.
The relative velocity of wind w.r.t. the boat is,
Since Y component of velocity is approximately zero, hence the flag will flutter almost due east.