Question

A car moves in a semi-circular track of radius 700m. If it starts from one end of the track and stops at the other end, the displacement of the car is
A) $2200m$
B) $700m$
C) $1400m$
D) $800m$

Answer 1

Recall the concept of displacement. Displacement is defined as to how far the object has traveled. It shows the overall change in the position of an object. It is a vector quantity. It is the act of moving something from its place.

Complete step by step answer:
It is given that the car is moving in a semi-circular track and also the radius is given.
If the car is starting from one end and stopping at the other end, then the displacement of the car will be equal to the diameter of the track.
Given that the radius of the track is, $r = 700m$
Since the radius of a circle is the half of its diameter, then if d is the diameter then the relation between radius and diameter is given by,
$d = 2r$
Substitute the value of r in the above relation and evaluate the value of d,
$\Rightarrow d = 2 \times 700$
$\Rightarrow d = 1400m$

Hence if the car starts from one end of the track and ends at the other end then the displacement of the car is $1400m$. Therefore option C is the right answer.

Note:
It is to be noted that the term distance and displacement are not the same. They are completely different. Distance shows the total path covered by anybody while the displacement is the shortest path covered by a body. Also, distance traveled by a body is never zero whereas the displacement of a body can be zero. Distance will always be either equal to or greater than the displacement.