question_answer

A man moves 20 m North, then 10 m East and then 10\[\sqrt{2}\] m South-West, his displacement is

A)                  20 m North

B)                  10\[\sqrt{2}\] m North-West

C)                  10\[\sqrt{2}\]m South-East

D)                  10 m North

Correct Answer: B

Solution :

                                                  \[v=\frac{{{v}_{1}}+{{v}_{2}}}{2}\]                 \[v=\frac{5\times {{10}^{6}}+2\times {{10}^{6}}}{2}=\frac{7}{2}\times {{10}^{6}}\]                 \[d=v\times t\]                 \[t=\frac{d}{v}=\frac{2.1\times {{10}^{-4}}\times {{10}^{-2}}}{\frac{7}{2}\times {{10}^{6}}}\]                 \[t=6\times {{10}^{-13}}s\]