question_answer

A boy walks uniformally along the sides of a rectangular park of size 400 m× 300 m, starting from one corner to the other corner diagonally opposite. Which of the following statement is incorrect                                 [HP PMT 1999]

A)            He has travelled a distance of 700 m

B)            His displacement is 700 m

C)            His displacement is 500 m

D)            His velocity is not uniform throughout the walk

Correct Answer: B

Solution :

                     Displacement \[\overrightarrow{AC}=\overrightarrow{AB}+\overrightarrow{BC}\]                    \[AC=\sqrt{{{(AB)}^{2}}+{{(BC)}^{2}}}=\sqrt{{{(400)}^{2}}+{{(300)}^{2}}}=500m\]                    Distance \[=AB+BC=400+300=700m\]