Brownian motion

(noun)

Random motion of particles suspended in a fluid, arising from those particles being struck by individual molecules of the fluid.

Related Terms

Examples of Brownian motion in the following topics:

  • Avogador's Number

    • In his study on Brownian motion in 1905, Albert Einstein proposed that this constant could be determined based on the quantities observable in Brownian motion.

  • Overview of Temperature and Kinetic Theory

    • The kinetic theory of gases describes a gas as a large number of small particles (atoms and molecules) in constant, random motion.
    • The kinetic theory of gases describes a gas as a large number of small particles (atoms or molecules), all of which are in constant, random motion.
    • Kinetic theory explains macroscopic properties of gases (such as pressure, temperature, and volume) by considering their molecular composition and motion.
    • Essentially, the theory posits that pressure is due not to static repulsion between molecules (as was Isaac Newton's conjecture) but rather due to collisions between molecules moving at different velocities through Brownian motion.

  • Defining Kinematics

    • Kinematics is the study of the motion of points, objects, and groups of objects without considering the causes of its motion.
    • Kinematics is the branch of classical mechanics that describes the motion of points, objects and systems of groups of objects, without reference to the causes of motion (i.e., forces).
    • The study of kinematics is often referred to as the "geometry of motion."
    • Objects are in motion all around us.
    • The word "kinematics" comes from a Greek word "kinesis" meaning motion, and is related to other English words such as "cinema" (movies) and "kinesiology" (the study of human motion).

  • Circular Motion

    • Uniform circular motion describes the motion of an object along a circle or a circular arc at constant speed.
    • It is the basic form of rotational motion in the same way that uniform linear motion is the basic form of translational motion.
    • However, the two types of motion are different with respect to the force required to maintain the motion.
    • Let us consider Newton's first law of motion.
    • Therefore, uniform linear motion indicates the absence of a net external force.

  • Overview of Non-Uniform Circular Motion

    • Non-uniform circular motion denotes a change in the speed of a particle moving along a circular path.
    • What do we mean by non-uniform circular motion?
    • The answer lies in the definition of uniform circular motion, which is a circular motion with constant speed.
    • The circular motion adjusts its radius in response to changes in speed.
    • In non-uniform circular motion, the magnitude of the angular velocity changes over time.

  • Constant Acceleration

    • Analyzing two-dimensional projectile motion is done by breaking it into two motions: along the horizontal and vertical axes.
    • Projectile motion is the motion of an object thrown, or projected, into the air, subject only to the force of gravity.
    • The motion of falling objects is a simple one-dimensional type of projectile motion in which there is no horizontal movement.
    • The key to analyzing two-dimensional projectile motion is to break it into two motions, one along the horizontal axis and the other along the vertical.
    • We analyze two-dimensional projectile motion by breaking it into two independent one-dimensional motions along the vertical and horizontal axes.

  • Motion Diagrams

    • A motion diagram is a pictorial description of an object's motion and represents the position of an object at equally spaced time intervals.
    • A motion diagram is a pictorial description of the motion of an object.
    • For this reason, a motion diagram is more information than a path diagram.
    • is a motion diagram of a simple trajectory.
    • Motion diagram of a puck sliding on ice.

  • Simple Harmonic Motion and Uniform Circular Motion

    • Simple harmonic motion is produced by the projection of uniform circular motion onto one of the axes in the x-y plane.
    • Uniform circular motion describes the motion of a body traversing a circular path at constant speed.
    • There is an easy way to produce simple harmonic motion by using uniform circular motion.
    • The next figure shows the basic relationship between uniform circular motion and simple harmonic motion.
    • Describe relationship between the simple harmonic motion and uniform circular motion

  • A Quantitative Interpretation of Motional EMF

    • A a motional EMF is an electromotive force (EMF) induced by motion relative to a magnetic field B.
    • An electromotive force (EMF) induced by motion relative to a magnetic field B is called a motional EMF.
    • Therefore, the motional EMF over the length L of the side of the loop is given by $\varepsilon_{motion} = vB \times L$ (Eq. 1), where L is the length of the object moving at speed v relative to the magnet.
    • From Eq. 1 and Eq. 2 we can confirm that motional and induced EMF yield the same result.
    • (a) Motional EMF.

  • Helical Motion

    • Helical motion results when the velocity vector is not perpendicular to the magnetic field vector.
    • In the section on circular motion we described the motion of a charged particle with the magnetic field vector aligned perpendicular to the velocity of the particle.
    • This produces helical motion (i.e., spiral motion) rather than a circular motion.
    • Uniform circular motion results.
    • Describe conditions that lead to the helical motion of a charged particle in the magnetic field