Kinematics Question 349
Question: A person moves 30 m north and then 20 m towards east and finally $ 30\sqrt{2} $ m south-west direction. The displacement of the person from the origin
Options:
A) 10 m along north
B) 10 m along south
C) 10 m along west
D) Zero
Show Answer
Answer:
Correct Answer: C
Solution:
$ \overline{OA}=0\overset\frown{i}+30\overset\frown{j}, $
$ \overrightarrow{AB}=20\overset\frown{i}+0\overset\frown{j}, $
$ \overline{BC}=-30\sqrt{2}\cos 45{}^\circ \overset\frown{i}-30\sqrt{2}\sin 45{}^\circ \overset\frown{j} $
$ =-30\overset\frown{i}-30\overset\frown{j} $
$ \therefore \text{Net desplacement,} $
$ \text{OC=OA+AB+BC=}-10\overset\frown{i}+0\overset\frown{j} \text{ OC }\text{ =10m} $
