What is how to find displacement?

To find displacement, you need to understand the difference between it and distance.

  • Displacement is a vector quantity that refers to "how far out of place an object is"; it is the object's overall change in position. It's the shortest distance from the initial to the final position. So, it involves both magnitude (how far) and direction.

  • Distance is a scalar quantity that refers to "how much ground an object has covered" during its motion.

Here's how to find displacement:

  1. Identify the Initial and Final Positions: The most important step is to clearly define the starting point (initial position) and ending point (final position) of the object's movement.

  2. Determine the Direction: Displacement involves direction. You must specify the direction from the initial position to the final position (e.g., North, South, East, West, up, down, or using angles).

  3. Calculate the Straight-Line Distance: Find the shortest straight-line distance between the initial and final positions. This is the magnitude of the displacement.

    • One-Dimensional Motion: If the object moves along a straight line (e.g., along the x-axis), the displacement is simply the difference between the final position (x<sub>f</sub>) and the initial position (x<sub>i</sub>): Δx = x<sub>f</sub> - x<sub>i</sub>. The sign (+ or -) indicates the direction.

    • Two-Dimensional Motion (or Higher): If the motion is in two or more dimensions, you may need to use the Pythagorean theorem or vector addition to find the magnitude and direction of the displacement. If the initial position is (x<sub>i</sub>, y<sub>i</sub>) and the final position is (x<sub>f</sub>, y<sub>f</sub>), then:

      • Displacement in x-direction: Δx = x<sub>f</sub> - x<sub>i</sub>
      • Displacement in y-direction: Δy = y<sub>f</sub> - y<sub>i</sub>
      • Magnitude of displacement: √(Δx² + Δy²)
      • Direction can be found using trigonometric functions (e.g., tangent) if needed.
  4. Specify the Direction: Combine the magnitude (the straight-line distance) with the direction to fully describe the displacement.

Example:

A person walks 5 meters East and then 3 meters North.

  • Initial position: (0,0)

  • Final position: (5,3)

  • Displacement in x-direction: 5 - 0 = 5 meters

  • Displacement in y-direction: 3 - 0 = 3 meters

  • Magnitude of displacement: √(5² + 3²) = √34 ≈ 5.83 meters

  • Direction: North-East (You could use trigonometry to find the exact angle relative to the East direction, but specifying North-East is sufficient in many cases.)

Therefore, the displacement is approximately 5.83 meters North-East.

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