Question

An aeroplane moves 400 m towards the north, 300 m towards west and then 1200 m vertically upwards, then its displacement from the initial position is:

• A. 1600m
• B. 1800m
• C. 1500m
• D. 1300m

Answer 1

Answer: (D)

1300m

Answer 2

Taking west as x axis, north as y axis and upward direction as z axis then position vector of the aeroplane taking starting point as origin

$\overrightarrow{r}$ = 300i + 400j + 1200k

Displacement is equal to length of the position vector

= $\sqrt{300^{2} + 400^{2} + 1200^{2}}$ = 1300 m.