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.
Rest :-
If any object does not change its position with respect to time and its surroundings, then it is called at rest.
Motion:-
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
Distance :-
The length of the path covered by a body in a particular time interval is called diatanced.
Displacement :-
The shortest distance between the initial and final points in a particular direction is called displacement.
Speed :-
The rate of change of distance is called speed.
It is a scalar quantity and its unit is m/s.
Velocity :-
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.
Acceleration :-
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.
