# An object travels North at  5 m/s for 2 s and then travels South at  1 m/s for  2 s. What are the object's average speed and velocity?

Mar 14, 2018

Total distance travelled by the object is $5 \cdot 2 + 1 \cdot 2 = 12 m$

And,net displacement of the object is $1 \cdot 2 - 5 \cdot 2 = - 8 m$

negative sign means direction of displacement is towards North.

Now,average speed =Total distance covered/total time taken=$\left(\frac{12}{4}\right) = 3 m {s}^{-} 1$

And,average velocity =Total displacement/Total time taken $= - \frac{8}{4} = - 2 m {s}^{-} 1$ and its direction is towards North.

Remember average speed is a scalar quantity wheras average velocity is a vector quantity