When a train is at rest, rain drops fall vertically. When it moves along east with a velocity equal to that of rain, the rain will appear to fall, for a passenger in the train

A man standing on a road hold his umbrella at $30^° $ with the vertical to keep the rain away. He throws the umbrella and starts running at $10\, km/hr$. He finds that raindrops are hitting his head vertically, the speed of raindrops with respect to the road will be......... $km/hr$

A girl standing at point $P$ on a beach wishes to reach a point $Q$ in the sea as quickly as possible. She can run at $6 \,kmh ^{-1}$ on the beach and swim at $4 \,kmh ^{-1}$ in the sea. She should take the path

A river is flowing from east to west at a speed of $5\, m/min$ A man on south bank of river, capable of swimming $10\,m/min$ in still water, wants to swim across the river in shortest time. He should swim

The speed of a swimmer is $4\,km\,h ^{-1}$ in still water. If the swimmer makes his strokes normal to the flow of river of width $1\,km$, he reaches a point $750 \,m$ down the stream on the opposite bank.The speed of the river water is $.........km h ^{-1}$

Aboat having a speed of $5\,\, km/hr$. in still water, crosses a river of width $1\,\, km$ along the shortest possible path in $15 \,\,minutes$. The speed of the river in $Km/hr.$