Brownian motion (named after Robert Brown, who first observed the motion in 1827, when he examined pollen grains in water), or pedesis (from Greek: πήδησις "leaping") is the assumably random movement of particles suspended in a fluid (i.e., a liquid such as water or a gas such as air) or the mathematical model used to describe such random movements, often called a particle theory.
The mathematical model of Brownian motion has several real-world applications. An often quoted example is stock market fluctuations. However, movements in share prices may arise due to unforeseen events which do not repeat themselves.
Brownian motion is among the simplest of the continuous-time stochastic (or probabilistic) processes, and it is a limit of both simpler and more complicated stochastic processes (see random walk and Donsker's theorem). This universality is closely related to the universality of the normal distribution. In both cases, it is often mathematical convenience rather than the accuracy of the models that motivates their use. This is because Brownian motion, whose time derivative is everywhere infinite, is an idealized approximation to actual random physical processes, which always have a finite time scale.

 

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circular motion

In physics, uniform circular motion describes the motion of a body traversing a circular path at constant speed. The distance of the body from the axis of rotation remains constant at all times. Though the body's speed is constant, its velocity is not constant: velocity, a vector quantity, depends on both the body's speed and its direction of travel. This changing velocity indicates the presence of an acceleration; this centripetal acceleration is of constant magnitude and directed at all times towards the axis of rotation. This acceleration is, in turn, produced by a centripetal force which is also constant in magnitude and directed towards the axis of rotation.

Movement and Position

It is very useful to be able to make predictions about the way moving objects behave.This text will be more use to you ,to have a simple idea about the way that objects move with depending the speed and acceleration.

Speed
what is speed?
Speed is the term used a great deal in everyday life.For example if you were told a car travelled 100 km s in  2 hours you would probably have no difficult in working out that the speed of the car was 50km/h .You would done a simple calculation using the following equation related to speed.

Speed=Distance 
             Time taken 
This is usually written using the symbol v for velocity.d for distance travelled and t for time  
v = d
     t
        

Basic Physics Concepts

Physics is a systematic study of the natural world, a discipline that attempts to quantify reality through a precise application of observation coupled with logic and reason. In order to make use of such a discipline, of course, there is certain foundational information that you must have first, in order to build upon it.
   physics is the scientific study of matter and energy and how they interact with each other.
This energy can take the form of motion, light, electricity, radiation, gravity . . . just about anything, honestly. Physics deals with matter on scales ranging from sub-atomic particles (i.e. the particles that make up the atom and the particles that make up those particles) to stars and even entire galaxies.