Question

Consider east as positive x-axis, north as positive y-axis. A girl walks `10 m` east first time than `10 m` in a direction `30^(@)` west of north for the second time and then third time in unknown direction and magnitude so as to return to her initial position. What is her third displacement in unit vector notation.?
A. `-5hat(i)-5sqrt(3)hat(j)`
B. `5hat(i)-5sqrt(3)hat(j)`
C. `-5hat(i)+5sqrt(3)hat(j)`
D. She cannot return

Answer 1

Correct Answer - A

`vec(s)_(1)+vec(s)_(2)+vec(s)_(3)= 0`
`10hat(i)+[10 sin 30(-hat(i))+10 cos 30 hat(j)]+vec(s)_(3)=0`
`(10-5)hat(i)+5sqrt(3)hat(j)+vec(s)_(3)=0`
`vec(s)_(3)= -5hat(i)-5sqrt(3)hat(j)`