question_answer

A person goes 10 km north and 20 km east. What will be displacement from initial point                                [AFMC 1994, 2003]

A)                 22.36 km

B)                             2 km

C)                 5 km     

D)                 20 km

Correct Answer: A

Solution :

                    \[\overrightarrow{AC}=\overrightarrow{AB}+\overrightarrow{BC}\] \[AC=\sqrt{{{(AB)}^{2}}+{{(BC)}^{2}}}\]                                 \[=\sqrt{{{(10)}^{2}}+{{(20)}^{2}}}\]                 \[=\sqrt{100+400}\]\[=\sqrt{500}\]\[=22.36\,km\]