project on rest and motion
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Answers
Answer:
The general study of the relationship between motion, force and energy is known as mechanics. It is subdivided into three parts i.e. kinematics, dynamics and statics. Kinematics deals with the study of the motion of the objects without taking into account the forces and energies that may be involved. The first thing we need to know is that there is no absolute rest or absolute motion. Rest and motion are relative terms.
In simple terms, an object that changes its position is said to be in motion while the opposite action causes an object to be at rest. However, perspective plays a huge role in it. Take the example of an atom which is always in motion but when we see an object in the macro world it seems to be at rest. Therefore, rest and motion both depend mainly on the frame of reference of the one who is observing the scene.
Explanation:
Rest: An object is said to be at rest if it does not change its position with respect to its surroundings with time.
Motion: An object is said to be in motion if the position changes with respect to it surrounding and time.
Frame of Reference
Suppose an object is placed on the table, it can be said that the object is at rest. If a person is standing on the moon he will find that earth is changing its position continuously and so are the table and the object. Thus, to locate the position of anything one needs to define a frame of reference. For instance, if we take the earth as a reference, then the object is at rest but if the moon is taken as reference, the object is in motion. A frame of reference can be inertial or non-inertial depending on whether it is at rest or constantly moving.
Rest and Motion Related Terms
Speed
The distance covered by a moving body in a unit time interval is called its speed. It can be either uniform or non-uniform. Its units are meters per second (m/s)
Speed = Distance Travelled / Time Taken
Speed is generally shown in a position-time graph.
Speed in position-time graph
Position-time graph.
Uniform motion: When a body covers equal distance in an equal interval of time.
Position-time graph.
Non-Uniform Motion: Body covers an unequal distance in equal interval of time.
Displacement
It is defined as the shortest distance between the initial position and the final position.
Velocity
Change in the displacement of the body with respect to time is called its velocity. it is a vector quantity i.e. it has both magnitude and direction.
Velocity = Displacement / Time
Uniform velocity: Magnitude and direction remain the same with respect to time.
Non-Uniform velocity: When the body covers unequal displacement in an equal interval of time in a particular direction or if the direction changes, it is said to be moving at non-uniform velocity.
Average velocity = Time displacement / Total Time Taken
Acceleration and Deceleration
A body is said to be accelerating if it gradually increases its velocity with respect to time.
Average Acceleration = Change in Velocity / Time taken = Δy / Δt
Instantaneous acceleration = a =\lim_{\Delta t \rightarrow 0}\frac{\Delta v}{\Delta t}a=lim
Δt→0
Δt
Δv
Centripetal Acceleration
When a body moves along a circular path of the radius R with constant speed (v), the velocity of the body keeps changing since the direction of the motion keeps changing. This change in velocity causes the body to experience an acceleration which is directed towards the centre of the circular path. This acceleration is called centripetal acceleration.
Equations of Uniformly Accelerated Motion
(Along straight line) If a body started its motion with initial velocity ‘u’ and attains final velocity ‘v’ in the time interval ‘t’. The assumption used in all the equations is that the body covers distance ‘s’ at constant acceleration.
These equations are as follows:
V = u + at
S = ut +½ at2
V2 = u2 + 2as
Important points:
Acceleration and deceleration are vector quantities with SI unit m / s2.
A body is said to be decelerating if its velocity decreases with time.
If acceleration does not change with time, it is said to be constant acceleration.
Replace ‘a’ with acceleration due to gravity ‘g’ for a freely falling body. Similarly, if the body is thrown vertically upwards replace ‘a’ with ‘-g’.
The slope of the displacement-time graph gives velocity and slope of the velocity-time graph give acceleration.
Displacement, Velocity and Time Graphs
Different cases of the displacement-time graph (is the angle of the slope).
Displacement-time graph
Displacement-time graph
Different cases of the velocity-time graph.
Velocity-time graph
Velocity-time graph
Types of Motion
Projectile Motion
The motion of a body when it is thrown or projected with some initial velocity in a plane is known as projectile motion.
Examples:
The motion of the golf ball.
The motion of a rocket after burn-out
The motion of a bomb dropped from an aeroplane etc.
Projectile motion is of two types;
Horizontal projection
Angular Projection
Horizontal Projection