Glossary

2.1 Displacement

3 min read•june 18, 2024

and are key concepts in understanding . tells us where an object is, while shows how far it's moved from its starting point. These ideas are crucial for describing and analyzing movement in physics.

and displacement might seem similar, but they're different. Distance is how far something travels, while displacement is the straight-line difference between start and end points. This distinction helps us understand an object's overall movement and path.

Understanding Displacement and Position

Position and displacement concepts

Top images from around the web for Position and displacement concepts

  • Displacement and Velocity Vectors – University Physics Volume 1 View original

    Is this image relevant?

  • Displacement · Physics View original

    Is this image relevant?

  • Displacement and Velocity Vectors – University Physics Volume 1 View original

    Is this image relevant?

1 of 3

Top images from around the web for Position and displacement concepts

  • Displacement and Velocity Vectors – University Physics Volume 1 View original

    Is this image relevant?

  • Displacement · Physics View original

    Is this image relevant?

  • Displacement and Velocity Vectors – University Physics Volume 1 View original

    Is this image relevant?

1 of 3
  • Position specifies an object's location in space relative to a reference point or origin
    • Represented by a position vector (r⃗\vec{r} or s⃗\vec{s})
    • Described using ((x,y,z)(x, y, z) in 3D space or (x,y)(x, y) in 2D space)
  • Displacement quantifies the change in an object's position
    • Represented by a (Δr⃗\Delta\vec{r} or Δs⃗\Delta\vec{s})
    • Calculated by subtracting the initial position vector from the final position vector (Δr⃗=r⃗f−r⃗i\Delta\vec{r} = \vec{r}_f - \vec{r}_i)
    • Considers only the initial and final positions, not the path traveled
    • Includes both and direction

Distance vs displacement in motion

  • Distance is a representing the total path length traveled by an object
    • Always positive or zero, regardless of direction
    • Does not indicate the direction of motion
  • Displacement is a vector quantity representing the shortest distance between initial and final positions
    • Can be positive, negative, or zero, depending on the direction of motion
    • Provides information about both magnitude and direction of motion
  • Significance in describing movement:
    • Distance useful for considering total ground covered or effort required
    • Displacement relevant for analyzing overall change in position or net result of motion

Calculation of displacement

  • Calculate displacement by subtracting the initial position vector from the final position vector
    • 1D: Δx=xf−xi\Delta x = x_f - x_i
    • 2D: Δr⃗=(xf−xi)i^+(yf−yi)j^\Delta\vec{r} = (x_f - x_i)\hat{i} + (y_f - y_i)\hat{j}
    • 3D: Δr⃗=(xf−xi)i^+(yf−yi)j^+(zf−zi)k^\Delta\vec{r} = (x_f - x_i)\hat{i} + (y_f - y_i)\hat{j} + (z_f - z_i)\hat{k}
  • Path taken between initial and final positions does not affect displacement calculation
    • Displacement depends only on initial and final position vectors

Equality of distance and displacement

  • Displacement and are equal when:
    1. Object moves in a straight line from initial to final position
    2. Object returns to its initial position (zero displacement)
  • Displacement and distance traveled are different when:
    1. Object follows a curved or non-linear path between initial and final positions
    2. Object changes direction during motion
  • Examples:
    • Walking 5 m east and 5 m west results in 10 m distance traveled but zero displacement
    • Car driving one lap around a circular track has non-zero distance traveled but zero displacement (returns to starting point)

Motion and Kinematics

  • Motion describes the change in position of an object over time
  • is the branch of physics that studies motion without considering the forces causing it
  • refers to the path that a moving object follows through space
  • A is a coordinate system used to describe the position and motion of objects

Key Terms to Review (16)

Coordinates: Coordinates are a set of numbers or values that uniquely identify the position or location of a point in a given space or system. They provide a way to describe and represent the spatial arrangement of objects or locations in a standardized and quantifiable manner.
Displacement: Displacement is a vector quantity that refers to the change in position of an object. It has both magnitude and direction, indicating how far and in what direction the object has moved from its initial position.
Displacement: Displacement is the change in position of an object, measured from a reference point or origin. It describes the straight-line distance and direction an object has moved, without regard to the path taken.
Displacement Vector: A displacement vector is a directed line segment that represents the change in position of an object. It describes the distance and direction an object has moved from its initial location to its final location.
Distance: Distance is the total path length traveled by an object, regardless of its direction. It is a scalar quantity and always positive.
Distance traveled: Distance traveled is the total length of the path taken by an object in motion from its starting point to its ending point. It is a scalar quantity and does not depend on direction.
Kinematics: Kinematics is the branch of physics that studies the motion of objects without considering the forces that cause the motion. It focuses on parameters such as position, velocity, acceleration, and time, allowing us to describe how an object moves in space over time and understand various forms of motion.
Magnitude: Magnitude is a measure of the size or scale of a quantity, representing its absolute or relative value. It is a fundamental concept in physics, particularly in the context of vectors, forces, and displacement.
Motion: Motion is the change in position of an object over time. It is a fundamental concept in physics that describes how objects move through space, including their speed, direction, and acceleration.
Position: Position refers to the specific point in space that an object occupies, typically described using coordinates relative to a reference point. It is a vector quantity that has both magnitude and direction.
Position: Position refers to the location of an object or a particle in space, typically described using a coordinate system. It is a fundamental concept in physics that is crucial for understanding various topics, including displacement, motion, and the Heisenberg Uncertainty Principle.
Rectilinear Motion: Rectilinear motion is a type of motion where an object moves in a straight line, without any change in direction. It is a fundamental concept in classical mechanics and is often used to describe the motion of objects under the influence of constant forces.
Reference Frame: A reference frame is a coordinate system used to describe the position, motion, and other physical quantities of an object or event. It provides a frame of reference from which measurements and observations can be made. This term is crucial in understanding various topics in physics, including displacement, one-dimensional kinematics, graphical analysis of motion, and the concepts of simultaneity and time dilation.
Scalar Quantity: A scalar quantity is a physical quantity that has magnitude, or size, but no direction. It is fully described by a single numerical value and the appropriate unit of measurement.
Trajectory: Trajectory is the path that a moving object follows through space as a function of time. It is determined by factors such as initial velocity, angle of launch, and the forces acting on the object (e.g., gravity).
Trajectory: A trajectory is the path or curve that an object follows through space over time. It describes the motion and position of an object as it moves from one point to another, taking into account factors such as initial position, velocity, acceleration, and the effects of forces acting on the object.
© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.
Back
Practice QuizGlossary
Practice QuizGlossary
Next guide