Question 283 of 949
A hiker walks 3 km east and then 4 km north. What is the total displacement from the starting point to the final position of the hiker?
Correct Answer:
A
Explanation
To determine the total displacement of the hiker from the starting point to the final position, we need to analyze the situation step by step.
### Step 1: Understanding Displacement
Displacement is defined as the shortest straight-line distance from the initial position to the final position, along with the direction. It is a vector quantity, meaning it has both magnitude and direction.
### Step 2: Analyzing the Hiker's Path
The hiker walks:
- 3 km east
- 4 km north
We can visualize this movement on a coordinate system:
- Starting point (0, 0)
- After walking 3 km east, the hiker is at (3, 0).
- After walking 4 km north, the hiker is at (3, 4).
### Step 3: Calculating the Displacement
To find the displacement, we can use the Pythagorean theorem. The displacement forms a right triangle where:
- One leg (eastward movement) = 3 km
- The other leg (northward movement) = 4 km
According to the Pythagorean theorem:
\[
d = \sqrt{x^2 + y^2}
\]
where \(d\) is the displacement, \(x\) is the distance east, and \(y\) is the distance north.
Substituting the values:
\[
d = \sqrt{(3 \text{ km})^2 + (4 \text{ km})^2}
\]
\[
d = \sqrt{9 \text{ km}^2 + 16 \text{ km}^2}
\]
\[
d = \sqrt{25 \text{ km}^2}
\]
\[
d = 5 \text{ km}
\]
### Step 4: Conclusion
The total displacement from the starting point to the final position of the hiker is **5 km**.
### Step 5: Evaluating the Options
Now, let's evaluate the provided options:
- **A. 5 km** - This is the correct answer, as calculated above.
- **B. 7 km** - This option is incorrect because it does not represent the shortest distance between the starting and ending points.
- **C. 10 km** - This option is incorrect as it suggests a longer distance than the actual displacement.
- **D. 12 km** - This option is also incorrect, as it is significantly greater than the calculated displacement.
### Common Pitfalls
- **Confusing distance with displacement**: Distance is the total path length traveled, while displacement is the straight-line distance from start to finish.
- **Forgetting to use the Pythagorean theorem**: When dealing with right triangles, always remember to apply this theorem to find the resultant displacement.
### Revision Summary
- Displacement is the shortest distance from the starting point to the final position.
- Use the Pythagorean theorem to calculate displacement in right triangles.
- The hiker's path forms a right triangle with legs of 3 km and 4 km.
- The correct displacement is 5 km, which is option A.