question_answer

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

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

B)  \[40\,m{{s}^{-1}}\] south-west

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

D)  \[40\,m{{s}^{-1}}\] north-west

Correct Answer: A

Solution :

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