Question 275 of 949
A person walks 3 meters east, then 4 meters north. What is their total displacement from the starting point?
- 3 meters
- 4 meters
- 5 meters
- 7 meters
Correct Answer:
C
Explanation
To determine the total displacement of a person who walks 3 meters east and then 4 meters north, we can visualize the situation and apply the Pythagorean theorem. Let's break this down step-by-step.
### Step 1: Understanding Displacement
Displacement is a vector quantity that refers to the shortest distance from the initial position to the final position, along with the direction. It is different from distance, which is a scalar quantity that only considers how much ground is covered, regardless of direction.
### Step 2: Visualizing the Movement
1. **Starting Point**: Imagine a coordinate system where the starting point is at the origin (0, 0).
2. **First Movement**: The person walks 3 meters east. This can be represented as moving from (0, 0) to (3, 0).
3. **Second Movement**: Then, the person walks 4 meters north. This movement takes them from (3, 0) to (3, 4).
### Step 3: Finding the Displacement
Now, we need to find the straight-line distance from the starting point (0, 0) to the final position (3, 4). This forms a right triangle where:
- One leg (eastward movement) is 3 meters.
- The other leg (northward movement) is 4 meters.
### Step 4: Applying the Pythagorean Theorem
To find the hypotenuse (which represents the displacement), we can use the Pythagorean theorem, which states:
\[
c^2 = a^2 + b^2
\]
where:
- \(c\) is the hypotenuse (displacement),
- \(a\) is one leg (3 meters),
- \(b\) is the other leg (4 meters).
Substituting the values:
\[
c^2 = 3^2 + 4^2
\]
\[
c^2 = 9 + 16
\]
\[
c^2 = 25
\]
Taking the square root of both sides gives:
\[
c = \sqrt{25} = 5 \text{ meters}
\]
### Conclusion
The total displacement from the starting point is **5 meters**. Therefore, the correct option is **C**.
### Step 5: Analyzing Other Options
- **Option A (3 meters)**: This option only considers the eastward movement and ignores the northward movement. It does not represent the total displacement.
- **Option B (4 meters)**: This option only considers the northward movement and ignores the eastward movement. Like option A, it does not represent the total displacement.
- **Option D (7 meters)**: This option incorrectly adds the two movements (3 meters + 4 meters) as if they were in a straight line. However, displacement is not simply the sum of the distances traveled in different directions.
### Revision Summary
- Displacement is the shortest distance from the starting point to the final position, considering direction.
- Use the Pythagorean theorem to calculate displacement when movements are at right angles.
- In this case, the movements create a right triangle with legs of 3 meters and 4 meters.
- The total displacement calculated is 5 meters, making option C the correct answer.