Question 280 of 949
A person walks 3 meters east, then 4 meters north. What is the total displacement from the starting point to the final position?
- 5 meters
- 7 meters
- 12 meters
- 1 meter
Correct Answer:
A
Explanation
**Correct Option: A. 5 meters**
### Step-by-Step Explanation
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 the total path traveled.
2. **Visualizing the Movement**:
- The person first walks **3 meters east**.
- Then, they walk **4 meters north**.
- To visualize this, imagine a coordinate system where the starting point is at the origin (0,0). Moving east means moving along the x-axis, and moving north means moving along the y-axis.
3. **Calculating the Final Position**:
- After walking 3 meters east, the new position is (3, 0).
- After walking 4 meters north from (3, 0), the final position is (3, 4).
4. **Using the Pythagorean Theorem**:
- To find the displacement, we can treat the movement as a right triangle where:
- One leg (eastward movement) is 3 meters.
- The other leg (northward movement) is 4 meters.
- The displacement (hypotenuse of the triangle) can be calculated using the Pythagorean theorem:
\[
d = \sqrt{x^2 + y^2}
\]
where \(x\) is the eastward distance and \(y\) is the northward distance.
- Plugging in the values:
\[
d = \sqrt{(3 \, \text{m})^2 + (4 \, \text{m})^2} = \sqrt{9 + 16} = \sqrt{25} = 5 \, \text{m}
\]
5. **Conclusion**: The total displacement from the starting point to the final position is **5 meters**.
### Explanation of Other Options
- **Option B (7 meters)**: This option might confuse distance traveled with displacement. The total distance walked is 3 meters + 4 meters = 7 meters, but this is not the displacement, which is the straight-line distance from start to finish.
- **Option C (12 meters)**: This option likely results from misunderstanding the path taken. It could be mistakenly calculated by adding the two distances walked (3 + 4 + 5), but this does not apply to displacement.
- **Option D (1 meter)**: This option is incorrect as it does not reflect any logical calculation based on the movements described. It may arise from a misunderstanding of how to calculate displacement.
### Common Pitfalls
- Confusing distance with displacement: Remember that distance is the total path length, while displacement is the straight-line distance from start to finish.
- Forgetting to use the Pythagorean theorem for right triangles: Always check if the movements form a right triangle when calculating displacement.
### 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 form a right triangle.
- The correct displacement for the given movements (3 meters east and 4 meters north) is 5 meters.
- Always differentiate between total distance traveled and displacement in physics problems.