Video Transcript
The car shown is at the center of a
circle. The car moves a distance of 30
meters, and its final position is 30 meters away from its starting position. Did the car move in a single
direction? (A) Yes, (B) no.
The question asks us about the path
taken by a car that ends up 30 meters from its starting position. This last phrase is the key to
answering this question correctly.
If the car ends up 30 meters away
from its starting position, it means that the car didn’t just move backwards and
forwards over the same spot until it had traveled a cumulative distance of 30 meters
like this. No, the question states that the
car’s final position is 30 meters away from its starting position. In other words, the car has a
displacement of 30 meters from its starting position in the center of a circle. To answer this question, we need to
understand the difference between the displacement of an object and the distance
that the object traveled.
Distance is a scalar quantity and
is equal to the length of the path that an object took to get from one position to
another. For example, if an object traveled
along this path, then the distance it has traveled is equal to the total length of
the pink line. On the other hand, displacement is
a vector quantity. Displacement is equal to the
distance between the start point and the end point of the object in a particular
direction. The displacement of an object is
only equal to the distance it has traveled when an object travels in a straight line
without changing direction.
In this question, we are told that
the car moves a distance of 30 meters and its final position is 30 meters away from
its starting position. In other words, the distance
traveled by the car and the magnitude of the car’s displacement are both equal to 30
meters. In order for this to be the case,
the car must have traveled in a straight line in a single direction.
The correct answer is therefore
option (A). Yes, the car did move in a single
direction.
