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
Due north
Due north-east
Due north-east with double the speed of river
None of these
Four persons $P, Q, R$ and $S$ are initially at the four corners of a square of side $d$. Each person now moves with a constant speed $v$ in such a way that $P$ always moves directly towards $Q, Q$ towards $R$. $R$ towards $S$, and $S$ towards $P$. The four persons will meet after time ........
The component of a vector along any other direction is
If the angle between two vectors $A$ and $B$ is $120^{\circ}$, its resultant $C$ will be
A boat is sent across a river with a velocity of $8\, km/hr$. If the resultant velocity of boat is $10 \,km/hr$, then velocity of the river is ........$km/hr$
Given $A =\hat{ i }+\hat{ j }+\hat{ k }$ and $B =-\hat{ i }-\hat{ j }-\hat{ k }$, then $( A - B )$ will make angle with $A$