# data[].attributes.body
Although it may seem safe to assume that one horsepower is the output a horse is capable of creating at any one time, that is incorrect. In fact, the maximum output of a horse can be up to 15 horsepower, and the maximum output of a human is a bit more than a single horsepower.

Does one horsepower equal one horse?

Not quite. It's a common misconception that one horsepower is equal to the peak power production of a horse, which is capable of a maximum of around 14.9 horsepower. By comparison, a human being is capable of approximately five horsepower at peak power production.

# data[].attributes.attachment_caption
Why doesn't the paper burn in case 1 whereas it does in case 2? [3 MARKS]

# data[].attributes.attachment_caption
Metal is a good conductor – paper over metal gets burned slower | Evan's Space

# data[].attributes.attachment_caption
Why a piece of paper is not burning when wrapped around metals (copper)? - Quora

# data[].attributes.attachment_caption
Amazing physics experiment with the burning paper

# data[].attributes.attachment_caption
Flexibility and extensibility in the titin molecule: analysis of electron microscope data - ScienceDirect

# data[].attributes.attachment_caption
7.4 Electron Microscope image of calcium carbonate molecules. | Download Scientific Diagram

# data[].attributes.attachment_caption
Segmented nanofibers of spider dragline silk: Atomic force microscopy and single-molecule force spectroscopy | PNAS

# data[].attributes.attachment_caption
First ever pictures of single proteins thanks to graphene sheet | New Scientist

# data[].attributes.body
kiến tha lá
lễ hội rước kiệu

# data[].attributes.attachment_link.title
Tạo lửa bằng cách đảo ngược quy trình rèn

# data[].attributes.attachment_caption
An amount of a gas substance, represented by a few particles. (a) In a... | Download Scientific Diagram

# data[].attributes.attachment_caption
Top 30 Leidenfrost Effect GIFs | Find the best GIF on Gfycat

# data[].attributes.attachment_caption
Top 30 Leidenfrost Effect GIFs | Find the best GIF on Gfycat

# data[].attributes.attachment_caption
How Hot Electrons Get Cool - FunsizePhysics

# data[].attributes.attachment_link.title
MISSING VOLUME - ENGLISH - Why does some volume disappear?

# data[].attributes.attachment_link.title
Explaining Why the Volume of an Alcohol and Water Solution Is Less Than Expected

# data[].attributes.attachment_link.description
Students pour 250 mL of water and 250 mL of ethyl alcohol into a graduated cylinder. The graduated cylinder shows a total volume of 480 mL. Why does the cylinder contain less than 500 mL of liquid?

# data[].attributes.attachment_link.title
Volume Reduction during mixing of ethanol and water

# data[].attributes.attachment_link.authors[].name
Chemistry Demo Lab Ohio State University

# data[].attributes.attachment_link.title
250+250=490 - missing volume when mixing water and ethanol

# data[].attributes.attachment_link.authors[].name
Chemistry Demo Lab Ohio State University

# data[].attributes.attachment_link.title
Volume Change when Mixing Alcohol and Water Explained

# data[].attributes.attachment_link.title
Albert Einstein’s theory of Brownian motion

# data[].attributes.attachment_link.description
Description of Albert Einstein’s theory of Brownian motion and how he derived the size of atoms.

# data[].attributes.body
Brownian Motion Examples

The motion of pollen grains on still water.

Movement of dust motes in a room (although largely affected by air currents)

Diffusion of pollutants in the air.

Diffusion of calcium through bones.

Movement of "holes" of electrical charge in semiconductors.

# data[].attributes.attachment_link.readable_text
This article was most recently revised and updated by

Brownian motion, also called Brownian movement, any of various physical phenomena in which some quantity is constantly undergoing small, random fluctuations. It was named for the Scottish botanist Robert Brown, the first to study such fluctuations (1827).

If a number of particles subject to Brownian motion are present in a given medium and there is no preferred direction for the random oscillations, then over a period of time the particles will tend to be spread evenly throughout the medium. Thus, if A and B are two adjacent regions and, at time t, A contains twice as many particles as B, at that instant the probability of a particle's leaving A to enter B is twice as great as the probability that a particle will leave B to enter A. The physical process in which a substance tends to spread steadily from regions of high concentration to regions of lower concentration is called diffusion. Diffusion can therefore be considered a macroscopic manifestation of Brownian motion on the microscopic level. Thus, it is possible to study diffusion by simulating the motion of a Brownian particle and computing its average behaviour. A few examples of the countless diffusion processes that are studied in terms of Brownian motion include the diffusion of pollutants through the atmosphere, the diffusion of "holes" (minute regions in which the electrical charge potential is positive) through a semiconductor, and the diffusion of calcium through bone tissue in living organisms.

Early investigations

The term "classical Brownian motion" describes the random movement of microscopic particles suspended in a liquid or gas. Brown was investigating the fertilization process in Clarkia pulchella, then a newly discovered species of flowering plant, when he noticed a "rapid oscillatory motion" of the microscopic particles within the pollen grains suspended in water under the microscope. Other researchers had noticed this phenomenon earlier, but Brown was the first to study it. Initially he believed that such motion was a vital activity peculiar to the male sex cells of plants, but he then checked to see if the pollen of plants dead for over a century showed the same movement. Brown called this a "very unexpected fact of seeming vitality being retained by these 'molecules' so long after the death of the plant." Further study revealed that the same motion could be observed not only with particles of other organic substances but even with chips of glass or granite and particles of smoke. Finally, in inarguable support of the nonliving nature of the phenomenon, he demonstrated it in fluid-filled vesicles in rock from the Great Sphinx.

Early explanations attributed the motion to thermal convection currents in the fluid. When observation showed that nearby particles exhibited totally uncorrelated activity, however, this simple explanation was abandoned. By the 1860s theoretical physicists had become interested in Brownian motion and were searching for a consistent explanation of its various characteristics: a given particle appeared equally likely to move in any direction; further motion seemed totally unrelated to past motion; and the motion never stopped. An experiment (1865) in which a suspension was sealed in glass for a year showed that the Brownian motion persisted. More systematic investigation in 1889 determined that small particle size and low viscosity of the surrounding fluid resulted in faster motion.

Einstein's theory of Brownian motion

Since higher temperatures also led to more-rapid Brownian motion, in 1877 it was suggested that its cause lay in the "thermal molecular motion in the liquid environment." The idea that molecules of a liquid or gas are constantly in motion, colliding with each other and bouncing back and forth, is a prominent part of the kinetic theory of gases developed in the third quarter of the 19th century by the physicists James Clerk Maxwell, Ludwig Boltzmann, and Rudolf Clausius in explanation of heat phenomena. According to the theory, the temperature of a substance is proportional to the average kinetic energy with which the molecules of the substance are moving or vibrating. It was natural to guess that somehow this motion might be imparted to larger particles that could be observed under the microscope; if true, this would be the first directly observable effect that would corroborate the kinetic theory. This line of reasoning led the German physicist Albert Einstein in 1905 to produce his quantitative theory of Brownian motion. Similar studies were carried out on Brownian motion, independently and almost at the same time, by the Polish physicist Marian Smoluchowski, who used methods somewhat different from Einstein's.

Einstein wrote later that his major aim was to find facts that would guarantee as much as possible the existence of atoms of definite size. In the midst of this work, he discovered that according to atomic theory there would have to be an observable movement of suspended microscopic particles. Einstein did not realize that observations concerning the Brownian motion were already long familiar. Reasoning on the basis of statistical mechanics, he showed that for such a microscopic particle the random difference between the pressure of molecular bombardment on two opposite sides would cause it to constantly wobble back and forth. A smaller particle, a less viscous fluid, and a higher temperature would each increase the amount of motion one could expect to observe. Over a period of time, the particle would tend to drift from its starting point, and, on the basis of kinetic theory, it is possible to compute the probability ( P) of a particle's moving a certain distance ( x) in any given direction (the total distance it moves will be greater than x) during a certain time interval ( t) in a medium whose coefficient of diffusion ( D) is known, D being equal to one-half the average of the square of the displacement in the x-direction. This formula for probability "density" allows P to be plotted against x. The graph is the familiar bell-shaped Gaussian "normal" curve that typically arises when the random variable is the sum of many independent, statistically identical random variables, in this case the many little pushes that add up to the total motion. The equation for this relationship is

The introduction of the ultramicroscope in 1903 aided quantitative studies by making visible small colloidal particles whose greater activity could be measured more easily. Several important measurements of this kind were made from 1905 to 1911. During this period the French physicist Jean-Baptiste Perrin was successful in verifying Einstein's analysis, and for this work he was awarded the Nobel Prize for Physics in 1926. His work established the physical theory of Brownian motion and ended the skepticism about the existence of atoms and molecules as actual physical entities.

Erik Gregersen.

# data[].attributes.attachment_link.description
Brownian motion, any of various physical phenomena in which some quantity is constantly undergoing small, random fluctuations. It was named for the Scottish botanist Robert Brown, the first to study such fluctuations (1827). If a number of particles subject to Brownian motion are present in a given

# data[].attributes.body
Brownian motion refers to the random movement of microscopic particles in a fluid, which was first observed and described by the Scottish botanist Robert Brown in 1827. Here are some common experiments used to demonstrate Brownian motion:

1. Microscope observation: One of the easiest ways to observe Brownian motion is to place a small amount of fine particles, such as pollen grains or smoke particles, in a drop of water or other fluid on a microscope slide. When viewed under a microscope, the particles will appear to move randomly and rapidly due to collisions with the fluid molecules.

2. Brownian motion apparatus: Another way to observe Brownian motion is by using a Brownian motion apparatus. This consists of a small glass or plastic container filled with water or another liquid, with tiny plastic or glass beads suspended in the liquid. As the beads move randomly, they reflect light and produce a visible pattern of motion.

3. Laser light scattering: Laser light scattering is a more advanced technique for observing Brownian motion. A laser beam is passed through a sample containing small particles, and the scattered light is measured and analyzed to determine the motion of the particles. This technique is often used in the study of colloidal systems, such as the behavior of proteins or nanoparticles in solution.

4. Computer simulations: Computer simulations can also be used to study Brownian motion. By modeling the behavior of particles in a fluid, researchers can investigate how various factors, such as particle size, temperature, and fluid viscosity, affect the motion of the particles. These simulations are often used to develop more accurate models of Brownian motion and to design new experiments to test these models.

# data[].attributes.attachment_link.title
Physics of Life - Brownian Motion and Brownian Motors

# data[].attributes.attachment_link.title
Random Force & Brownian Motion - Sixty Symbols