question_answer

A truck travelling due north at\[20\text{ }m{{s}^{-1}}\]turns west and travels with same speed. What is the change in velocity?

A)  \[20\sqrt{2}\,m{{s}^{-1}}\]south-west

B) \[40\text{ }m{{s}^{-1}}\]south-west

C)  \[\text{20}\sqrt{2}\text{ }m{{s}^{-1}}\]north-west

D) \[\text{40 }m{{s}^{-1}}\]north-west

Correct Answer: A

Solution :

  Change in velocity \[=\sqrt{{{(20)}^{2}}+{{(20)}^{2}}}=20\sqrt{2}\] along north-east or south-west