Introduction
The branch of Physics, which deals with the behaviour of moving objects, is known as mechanics. Mechanics is further divided into two sections namely Kinematics and Dynamics.
Motion and Rest
Imagine yourself sitting in a seat while travelling in a moving train. You observe no change in position with respect to the window. There is change of scene when you view through the window.
Types of Motion
There are three types of motion: Translatory motion, Rotatory motion, Vibratory motion.
Distance and Displacement
Distance is a scalar quantity. SI unit of distance is metre.Displacement is the shortest distance covered by a moving object from the point of reference (initial position of the body), in a specified direction.
Uniform Motion and Non-uniform Motion
When a body covers equal distances in equal intervals of time then the body is said to describe uniform motion.When a body moves unequal distances in equal intervals of time or vice-versa, then the body is said to describe non-uniform motion.
Speed
Speed can be defined as the distance covered by a moving object in unit time.
Distance-Time Table and Distance-Time Graph
A distance-time graph is a line graph showing the variation of distance with time.
Distance-Time Graph for Uniform Motion
The distance-time graph is a straight line showing that the motion is uniform.
Distance-Time Graph for Non - Uniform Motion
Graphs can be easily read at a glance.Plotting graphs takes less time and is more convenient.
Velocity
Velocity is defined as the distance travelled in a specified direction in unit time. The distance travelled in a specified direction is displacement.
Acceleration
All of us know that a car moving on road does not have a uniform velocity. Either the speed or the direction changes. Whenever a vehicle is speeding i.e., when the speed is increased we say that the vehicle is accelerating.
Uniform Velocity and Non-uniform Velocity
Thus a body is said to be moving with uniform velocity if it covers equal distances in equal intervals of time in a specified direction.A body is said to be moving with variable velocity if it covers unequal distances in equal intervals of time and vice-versa in a specified direction or if it changes the direction of motion.
Circular Motion
An object moving along a circular track with uniform speed is an example for a non - uniform motion because the direction of motion of the object goes on changing at every instant of time.
Velocity-Time Graph
The variation of velocity with time can be represented graphically to calculate acceleration exactly like we calculated speed from distance-time graph.
v-t Graph
The acceleration produced in a body.The distance covered by a moving object.We can derive the equations of motion.
Speed - Time Graph
To calculate the distance covered by a moving object from speed-time graph.
Equations of Motion
The variable quantities in a uniformly accelerated rectilinear motion are time, speed, distance covered and acceleration. Simple relations exist between these quantities.
Summary
When a body covers equal distances in equal intervals of time then the body is said to describe uniform motion.
Question and Answers
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Multiple Choice Questions
