A person walks 5 km north, then turns left and walks 3 km, then turns left again and walks 5 km. How far is he from the starting point?

Appeared in: NHM MP Staff Nurse - 2015

Explanation

The problem requires calculating the net displacement, which is the straight-line distance from the start to the end point, not the total distance traveled.
The first movement is 5 km North, and the third movement is 5 km South. These two movements are equal in magnitude and opposite in direction.
Because the North and South movements cancel each other out, the net vertical displacement is zero.
The only remaining displacement is the 3 km movement to the West. Therefore, the final distance from the starting point is 3 km.

Option B: This value represents the distance of the first and third individual legs of the journey, but it is not the final displacement from the starting point.
Option C: This is the sum of the first two legs of the journey (5 km + 3 km). This represents a portion of the total distance traveled, not the final displacement.
Option D: This is the sum of the North and South movements (5 km + 5 km). This incorrectly adds the distances instead of recognizing that they are in opposite directions and cancel each other out.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Direction and Distance Reasoning as background academic context rather than a clinical decision trigger.
While not a clinical question, the underlying skills of logical reasoning and spatial awareness are crucial for nurses.
These skills are applied daily when navigating large hospital complexes, locating equipment, or understanding anatomical directions (e.g., superior, inferior, lateral, medial).
Developing strong problem-solving abilities helps in clinical decision-making, such as prioritizing patient care or troubleshooting equipment issues under pressure.

How to Approach the Question

First, identify the starting point and visualize it as the origin (0,0) on a simple grid or map.
Second, break down the journey into individual steps, noting the direction (North, South, East, West) and distance for each.
Third, draw a simple diagram of the path. This is the most effective way to visualize the person's movement and final position.
Fourth, analyze the movements along the primary axes (North-South and East-West). Look for movements that are in opposite directions and can cancel each other out.
In this case, the 5 km North and 5 km South movements cancel, leaving only the 3 km West movement.
Finally, determine the straight-line distance from the starting point to the final position. This is the displacement, which is what the question is asking for.

Concept Tested & Keywords

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Practise the full NHM MP Staff Nurse - 2015

Attempt every question from this paper in a timed mock, then review the full solution for each one.