Chapter : Rest and Motion
Simple pendulum(image source: wikipedia.org)
In our daily life we see many objects that are either in rest position or Motion. eg- moving Trains, car ,cycle, etc and on other hand trees, houses, furnitures, etc are in rest position.
If any object does not change its position with respect to time and its surroundings, then it is called at rest.
If the position of any objects changes with the time and its surroundings, then it is said to be at the state of motion.
Types of motion
Rectilinear and Translatory motion :-
Circular Motion :-
when a body moves along a circular path, then its motion is called circular motion. In circular motion a body always accelerated towards the gravity.
Periodic Motion :-
Simple Harmonic Motion :-
If a body moves to and fro in a straight line about a fixed point or position, then the motion of the body is called Simple Harmonic Motion. eg – movement of a pendulum.
Oscillatory Motion :-
If a body repeats its movement after a regular interval of time about a fixed point, then the motion is called Oscillatory motion.
Projectile Motion :-
Projectile motion is a form of motion in which an object or particle is thrown near the earth’s surface, and its moves along a curved path under the action of gravity. The path of projectile is always parabolic.
For the maximum range of the projectile, the angle of projection should be 45°.
For maximum height of the projection, the angle of projection should be 90°.
Simple Pendulum :-
A simple Pendulum i s a point mass suspended from rigid support by means of an elastic inextensible string.
Where l = length of the string and g = acceleration due to gravity.
Some Basic Terms related with Motion
The length of the path covered by a body in a particular time interval is called diatanced.
The shortest distance between the initial and final points in a particular direction is called displacement.
The rate of change of distance is called speed.
It is a scalar quantity and its unit is m/s.
The rate of change of displacement is called velocity, i.e. Velocity = displacement/time.
It is a vector quantity and its unit is also m/s.It may be negative, zero or positive.
Uniform velocity :-
If a body covers equal displacements in equal interval of time, then it is said that the body is moving with uniform velocity.
Non-uniform Velocity :-
If a body covers unequal displacement in equal intervals of time, then it is said that the body is moving with non-uniform velocity.
It is the rate of change of velocity.It is a vector quantity. Its S.I. unit is m/s.
If it is positive, then it is known as acceleration. If it is zero, then the body is moving with a uniform velocity. If it is negative, then it is known as retardation.