Two cars start at the same time from in point and move alone two roads, at right angle to each other. The speeds are 36 km/hr and 48 km/hr respectively. After 15 sec distance between them will be :

Solution (By Examveda Team)

Distance travelled by the 1st car in 15 seconds
$$\eqalign{ & {\text{OA}} = \left( {36 \times \frac{5}{{18}}} \right) \times 15\,{\text{m}} \cr & \,\,\,\,\,\,\,\,\,\,\, = 150\,{\text{m}} \cr} $$
Distance travelled by the 2nd car in 15 seconds
$$\eqalign{ & {\text{OB}} = \left( {48 \times \frac{5}{{18}}} \right) \times 15\,{\text{m}} \cr & \,\,\,\,\,\,\,\,\,\, = 200\,{\text{m}} \cr} $$
∴ Distance between them after 15 seconds
$$\eqalign{ & {\text{AB}} = \sqrt {{\text{O}}{{\text{A}}^2} + {\text{O}}{{\text{B}}^2}} \cr & \,\,\,\,\,\,\,\,\,\, = \sqrt {{{150}^2} + {{200}^2}} \cr & \,\,\,\,\,\,\,\,\,\, = \sqrt {22500 + 40000} \cr & \,\,\,\,\,\,\,\,\,\, = \sqrt {62500} \cr & \,\,\,\,\,\,\,\,\,\, = 250\,{\text{m}} \cr} $$