question_answer

A body goes 20 km north and then 10 km due east. The displacement of body from Us starting point is:

A) 30 km                                   

B) 25.2 km

C) 22.36 km                             

D) 10 km

Correct Answer: C

Solution :

Body goes 20 km due north along \[\overrightarrow{\text{OA}}\]and then 10 km due east along \[\overrightarrow{\text{AB}}\]                                                          Net displacement \[=\sqrt{{{(OA)}^{2}}+{{(AB)}^{2}}}\]                                 \[=\sqrt{{{(20)}^{2}}+{{(10)}^{2}}}\]                                \[=\sqrt{400+100}\]                              \[=10\sqrt{5}\,\text{km = 22}\text{.36}\,\text{km}\]