PHYSICSPROJECT

CIRCULAR MOTION

INTRODUCTION TO MOTION

IN PHYSICS, MOTION IS A CHANGE IN POSITION OF AN OBJECT WITH RESPECT TO TIME AND ITS REFERENCE POINT. MOTION IS TYPICALLY DESCRIBED IN TERMS OF DISPLACEMENT, VELOCITY, ACCELERATION, AND TIME. MOTION IS OBSERVED BY ATTACHING A FRAME OF REFERENCE TO A BODY AND MEASURING ITS CHANGE IN POSITION RELATIVE TO ANOTHER BODY. A BODY WHICH DOES NOT MOVE IS SAID TO BE AT REST, MOTIONLESS, STATIONARY, OR TO HAVE CONSTANT POSITION. AN OBJECT'S MOTION CANNOT CHANGE UNLESS IT IS ACTED UPON BY A FORCE.

AN OBJECT'S MOMENTUM IS DIRECTLY RELATED TO THE OBJECT'S MASS AND VELOCITY, AND THE TOTAL MOMENTUM OF ALL OBJECTS IN A CLOSED SYSTEM DOES NOT CHANGE WITH TIME.

TYPES OF MOTION

There are three types of motion :- Uniform Motion:- A body is said to have a uniform

motion if it travels equal distances in equal intervals of time, no matter how small these intervals may be.

Example A vehicle running at a constant speed of 10m/sec ,will cover equal distances of 10metres every second, so its motion will be uniform.A distance-Time graph for uniform motion is a straight line.

Non-Uniform Motion:- A body is said to have a non- uniform motion if it travels unequal distances in equal intervals of time, no matter how small these intervals may be.Example A freely ball from a certain height covers unequal distances in equal intervals of time, so its motion is non uniform.Non uniform motion is also called accelerated motion.The distance-time graph is curved for non uniform motion.

WHAT IS CIRCULAR MOTION ?

In physics, circular motion is a movement of an object along the circumference of a circle or rotation along a circular path. It can be uniform, with constant angular rate of rotation (and constant speed), or non-uniform with a changing rate of rotation. The rotation around a fixed axis of a three-dimensional body involves circular motion of its parts. The equations of motion describe the movement of the center of mass of a body. Examples of circular motion include: an artificial satellite orbiting the Earth at constant height. A stone which is tied to a rope and is being swung in circles, a car turning through a curve in a race track.

An electron moving perpendicular to a uniform magnetic field, and a gear turning inside a mechanism.

TYPES OF CIRCULAR MOTION

There are two types of circular motion :- Uniform circular motion :-Uniform circular motion

can be described as the motion of an object in a circle at a constant speed. As an object moves in a circle, it is constantly changing its direction. At all instances, the object is moving tangent to the circle. Since the direction of the velocity vector is the same as the direction of the object's motion, the velocity vector is directed tangent to the circle as well. The animation in the next depicts this by means of a vector arrow.

Your speedometer tells you the magnitude of your car's velocity vector, so when you go around a curve while keeping your speedometer needle steady, you are executing uniform circular motion. If your speedometer reading is changing as you turn, your circular motion is non-uniform. Uniform circular motion is simpler to analyze mathematically, so we will attack it first and then pass to the non-uniform case.

VOCABULARY

• uniform circular motion — circular motion in which the magnitude of the velocity vector remains constant

• Non-uniform circular motion — circular motion in which the magnitude of the velocity vector changes

Summary

• If an object is to have circular motion, a force must be exerted on it toward the center of the circle. There is no outward force on the object; the illusion of an outward force comes from our experiences in which our point of view was rotating,

A PRESENTATION BY -VASUDHA ARORA

-IX-B -38