Question

A body moves in the southern direction for $10s$ at the speed of $10m{s}^{-1}$. It then starts moving in the eastern direction at the speed of $20m{s}^{-1}$ for $10s$. The magnitude of the average velocity is ________. The average speed is ________. The total displacement will be _________.

Answer 1

(Refer to Image)

Distance travelled in southern direction = $speed\times time=10\times 10=100m$

Distance travelled in eastern direction = $speed\times time=20\times 10=200m$

Average velocity= $\frac{Displacement}{\text{Total time}}$

$=\frac{\sqrt{5}\times 100}{20}$

$=5\sqrt{5}m/s$

Average speed= $\frac{\text{Total distance}}{\text{Total time}}=\frac{100+200}{20}=\frac{300}{20}=15m/s$

Displacement= $100\sqrt{5}m$ .