A Scooter is going towards east at 20m/s turn right through an angle of  90^o. If the speed of the scooter remains unchanged in taking this turn, the change in the velocity of the scooter is 

Initial velocity  $u=20m/s$
Final velocity  $V=20m/s$
Angle between  $\overline{u}and\overline{V}={90}^{\mathrm{o}}$
$\therefore$ The magnitude of change in velocity is
$\begin{array}{l}\left|\overrightarrow{\mathrm{\Delta }V}\right|=|\overline{V}-\overline{u}|\\ =\sqrt{V^2+u^2-2Vu\cos \theta }\\ =\sqrt{V^2+u^2}\left(\cos \theta =\cos {90}^{\circ }=0\right)\\ =\sqrt{{20}^2+{20}^2}=20\sqrt{2}\\ =20\times 1.414\\ =28.28\mathrm{m}/\mathrm{s}\end{array}$