Question

A car travels from stop A to stop B with a speed of 30 km/h and then returns back to A with a speed of 50 km/h. Find the displacement of the car.

Answer 1

Hint: We are given a car that travels from A to B and then back to A. We are asked to find the displacement of the car in its total journey. By finding the minimum distance between the initial and final position of the car we will get the solution.

Complete answer:
In the question we are given a car which travels from A to B and then back to A.
The velocity of the car from stop A to stop B is given as 30 km/h and from stop B to A is given as 50 km/h.
Consider the figure given below which shows us the given situation.

We are asked to find the displacement of the car in its total journey.
We know that displacement of a body is the minimum distance between the initial position and final position of the body.
Here we know that the car starts from the stop A, travels to stop B and returns back to A. Therefore the initial position and final position of the car is stop A.
Therefore the displacement of the car is the distance from stop A to stop A itself, which is zero.
That is the displacement of the car in the given situation is zero.

Note:
Displacement is a vector quantity (a quantity with both magnitude and direction) which is simply defined as the overall change in the position of a body.
When the initial and final positions of a body are the same, then we say that the body has no displacement even though it has traveled some distance.