A bus is moving on a straight road towards north with a uniform speed of $50\; km / hour$ then it turns left through $90^{\circ} .$ If the speed remains unchanged after turning, the increase in the velocity of bus in the turning process is
$50 \;km / hr$ along west
$0$
$70.7 \;km / hr$ along south-west direction
$70.7\; km / hr$ along north-west direction
Which of the following is independent of the choice of co-ordinate system
If $\vec{P}+\vec{Q}=\overrightarrow{0}$, then which of the following is necessarily true?
The resultant of two vectors $\overrightarrow P $ and $\overrightarrow Q $ is $\overrightarrow R .$ If $Q$ is doubled, the new resultant is perpendicular to $P$. Then $R $ equals
The vectors $\vec{A}$ and $\vec{B}$ are such that
$|\vec{A}+\vec{B}|=|\vec{A}-\vec{B}|$
The angle between the two vectors is