In a harbour, wind is blowing at the speed of 72 km and the flag on the mast of a boat anchored in the harbour flutters along N-E direction. If the boat starts moving at the speed of 51 km. to the north, what is the direction of the flag on the mast of the boat?
When the boat is anchored in the harbour, the flag flutters along the NE direction, so the velocity of the wind is along NE direction. When the boat starts moving along north direction, the flag with flutter along the direction of relative velocity of wind with respect to the boat.