Question

A car moves towards west at a speed of 5m/s for 10s. Then it turns and moves due to south with same speed for 5s. The average velocity of the car for complete journey is

Answer 1

av . velo.= total displacement/time
displacement= 5
$\frac{(5 \times 5 - 5 \times 10) }{10 + 5}$

Answer 2

Given :

Speed when the car travelling in west direction for 10 s (v) = 5 m/sec

Time taken to travel in east direction (T) = 5 sec

To Find :

The average velocity of the car for complete journey

Solution :

Distance travelled in west direction (D₁) = speed × time

                                                                  =  5 × 10

                                                                  = 50 m

Distance travelled in south direction (D₂) = speed × time

                                                                    =  5 × 5

                                                                    = 25 m

∴ Displacement of the car (s) = $\sqrt{50^2 + 25^2}$

                                                = $\sqrt{2500 + 625}$

                                                = $\sqrt{3125}$

                                                = 55.9 m

∴ Average velocity (V) = $\frac{Total Displacement}{Total Time }$

                                     = $\frac{55.9}{15}$

                                     = 3.73 m/sec

Therefore, The average velocity of the car for complete journey is 3.73 m/sec.