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Today in History – 14 May

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today in history 14 may

today in history 14 may

1657

Dharmavir Chhatrapati Sambhaji Maharaj was born at Purandar fort.

1787

On this day in 1787, delegates to the Constitutional Convention begin to assemble in Philadelphia to confront a daunting task: the peaceful overthrow of the new American government as defined by the Article of Confederation. Although the convention was originally supposed to begin on May 14, James Madison reported that a small number only had assembled. Meetings had to be pushed back until May 25, when a sufficient quorum of the participating states—Massachusetts, New York, New Jersey, Pennsylvania, Delaware, Virginia, North Carolina, South Carolina and Georgia—had arrived.

1864

On this day, Union and Confederate troops clash at Resaca, Georgia. This was one of the first engagements in a summer-long campaign by Union General William T. Sherman to capture the Confederate city of Atlanta. The spring of 1864 saw a determined effort by the Union to win the war through major offensives in both the eastern and western theaters. In the east, Union General Ulysses S. Grant took on Confederate General Robert E. Lee, while Sherman applied pressure on the Army of the Tennessee, under General Joseph Johnston, in the west. The Atlanta campaign was dictated by the hilly terrain of northern Georgia.

1904

The Third Olympiad of the modern era, and the first Olympic Games to be held in the United States, opens in St. Louis, Missouri. The 1904 Games were actually initially awarded to Chicago, Illinois, but were later given to St. Louis to be staged in connection with the St. Louis World Exposition. Like the Second Olympiad, held in Paris in 1900, the St. Louis Games were poorly organized and overshadowed by the world’s fair.

1907

Muhammad Ayub Khan, Pakistani president, was born.

1914

Ekanath Dattatreya Kulkarni, educationist and writer, was born at Bhaloni, Tal Pandharpur.

1923

Narayan Ganesh Chandavarkar, one of the founder members of Indian Congress and social reformer, passed away.

1954

President issued an order extending application of Indian Constitution to Kashmir with the concurrence of the State government.

1955

The Soviet Union and seven of its European satellites signed a treaty establishing the Warsaw Pact, a mutual defense organization that put the Soviets in command of the armed forces of the member states.

1956

Govt announced that decimal coinage to be introduced in India from April 1, 1957.

1960

The first plane of India flew upto New York.

1963

Dr. Raghuvir, a famous linguist and President of Jansangh, passed away.

1973

Skylab, America’s first space station, was successfully launched into an orbit around the earth. Eleven days later, U.S. astronauts Charles Conrad, Joseph Kerwin, and Paul Weitz made a rendezvous with Skylab, repairing a jammed solar panel and conducting scientific experiments during their 28-day stay aboard the space station.

1976

Pakistan and India agreed to resume diplomatic ties.

1978

Jagdishchandra Mathur, modern Hindi playwright, passed away.

1982

All India Radio renamed as ‘Akashwani’ but it’s Urdu service yet announces that it’s All India Radio.

1992

LTTE banned in India.

1994

LTTE banned for the second time under the Unlawful Activities (Prevention) Act, 1967.

1994

RBI announced tight monetary policy.

1996

H.D. Deve Gowda elected leader of the third front as its prime ministerial candidate.

2000

L. K. Advani, Union Home Minister, announced the extension of the ban on the LTTE by two more years.

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Newtonian Systems and Laws of Motion

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newtonian systems laws of motion

Table of Contents

  1. Introduction
  2. What Is a Newtonian System?
  3. Newton’s Three Laws of Motion
  4. Concept of Inertial Frames
  5. Force and Mass: The Core Ingredients
  6. Types of Forces in Newtonian Mechanics
  7. Free Body Diagrams and System Analysis
  8. Applications of Newton’s Laws
  9. Common Problems and Misconceptions
  10. Newton’s Laws in Non-Inertial Frames
  11. Limitations of Newtonian Mechanics
  12. Conclusion

1. Introduction

Classical mechanics, often referred to as Newtonian mechanics, is the foundational pillar of physics that governs the motion of everyday objects. It provides deterministic rules for understanding how forces affect motion and interaction. Despite being centuries old, it remains indispensable in most engineering applications, orbital dynamics, construction, machinery, and fluid systems. In fact, virtually every mechanical system, from a rolling ball to the motion of satellites, is first analyzed using Newtonian principles.

Isaac Newton’s formulation in the 17th century built upon the works of Galileo, Kepler, and Descartes, giving rise to a complete framework that could describe and predict motion accurately. The predictive power of Newton’s laws gave humanity control over physical systems and enabled the scientific revolution. While modern theories like quantum mechanics and general relativity refine or replace Newtonian ideas under specific conditions, Newtonian mechanics remains a crucial approximation in a wide variety of physical domains.

One of the reasons Newtonian mechanics is so enduring is its relative simplicity and intuitiveness. Unlike quantum theory, which defies classical logic, Newtonian systems operate on the assumption of an objective, continuous, and measurable reality. This makes it the first formal physics theory taught to students and used extensively in industrial design, aerospace dynamics, structural analysis, and robotics.

The development of Newtonian mechanics in the 17th century revolutionized physics by introducing a systematic way to describe and predict the motion of objects. At its heart lies the concept of a system, influenced by internal and external forces, governed by three foundational laws. This framework provides the basis for nearly all classical physics and underpins engineering, astronomy, and mechanics.

In this module, we delve deeply into Newtonian systems, their construction, and the laws of motion that describe their dynamics.


2. What Is a Newtonian System?

In physics, the term “system” refers to a portion of the universe selected for analysis. A Newtonian system implies that the laws governing its dynamics are rooted in Newton’s laws. This system could be a single particle, a rigid body, or a collection of interacting bodies, like those connected via pulleys or gears.

A system can be either open (interacting with its surroundings) or closed (isolated). The classification of internal vs. external forces becomes crucial when solving multi-body problems. In internal force models, Newton’s third law ensures conservation of momentum within the system. External forces dictate how the center of mass of a system will move.

These systems are especially useful when simplifying real-world problems. For instance, a vehicle moving on a road can be modeled as a Newtonian system by abstracting the car as a rigid body and incorporating friction, normal force, and engine thrust as acting forces. This abstraction helps engineers and physicists perform analysis, design, and predict behavior under varying conditions.

A Newtonian system refers to a collection of particles or bodies analyzed using Newton’s laws of motion. It can be as simple as a falling apple or as complex as a multi-body system of pulleys and connected masses.

Key features:

  • The system is analyzed within an inertial reference frame.
  • Interactions are described using forces.
  • The net external force determines the system’s acceleration.

3. Newton’s Three Laws of Motion

Let’s now explore the historical importance and modern implications of each of Newton’s laws:

  • First Law (Inertia) introduced the revolutionary idea that motion does not require force unless acceleration is involved. This contradicted Aristotelian physics, which claimed that continuous force was needed for motion. In space, where external forces like friction are absent, objects maintain constant velocity unless acted upon — a direct verification of this law.
  • Second Law is often considered the most powerful of the three. It bridges the gap between kinematics (description of motion) and dynamics (causes of motion). It introduced the concept that the rate of change of momentum depends on the net force applied. Today, it forms the basis of engine and rocket design, where forces are deliberately applied to produce controlled acceleration.
  • Third Law reflects the symmetrical nature of physical interactions. For example, when a swimmer pushes against water, the water pushes back with equal force, propelling the swimmer forward. This principle is fundamental to propulsion mechanisms, biomechanics, and molecular interactions.

First Law (Law of Inertia)

An object remains in a state of rest or uniform linear motion unless acted upon by a net external force.

\[\vec{F}_{\text{net}} = 0 \Rightarrow \vec{v} = \text{constant}\]


Second Law (Law of Acceleration)

The rate of change of momentum of a body is directly proportional to the net force acting on it.

\[\vec{F} = m \vec{a}\]

More generally:

\[\vec{F} = \frac{d\vec{p}}{dt}, \quad \text{where} \quad \vec{p} = m\vec{v}\]


Third Law (Action-Reaction Principle)

For every action, there is an equal and opposite reaction.

\[\vec{F}{AB} = -\vec{F}{BA}\]


4. Concept of Inertial Frames

An inertial frame of reference is one in which Newton’s first law holds. That is, any object not acted upon by a force remains in uniform motion.


5. Force and Mass: The Core Ingredients

Mass

Scalar quantity representing a body’s inertia.

Force

Vector quantity — the cause of acceleration.

The net force is the vector sum of all individual forces:

\[\vec{F}_{\text{net}} = \sum_i \vec{F}_i\]


6. Types of Forces in Newtonian Mechanics

Contact Forces

  • Spring Force:
    \[
    F = -kx
    \]
  • Frictional Force (kinetic):
    \[
    f_k = \mu_k N
    \]

Field Forces

  • Electrostatic Force (Coulomb’s Law):
    \[
    \vec{F}_e = k_e \frac{q_1 q_2}{r^2} \hat{r}
    \]
  • Magnetic Force:
    \[
    \vec{F}_m = q \vec{v} \times \vec{B}
    \]

7. Free Body Diagrams and System Analysis

Free body diagrams help isolate the object of interest and show all external forces acting on it.

Example: Inclined Plane

  • Gravitational component along incline:
    \[
    F_{\parallel} = mg \sin \theta
    \]
  • Normal force:
    \[
    N = mg \cos \theta
    \]

8. Applications of Newton’s Laws

Example 1: Accelerating Elevator

An elevator of mass ( m ) accelerates upward with acceleration ( a ).

  • Tension in cable:
    \[
    T = m(g + a)
    \]

If moving downward:

\[T = m(g – a)\]


Example 2: Pulley System

Two masses ( m_1 ) and ( m_2 ) connected over a frictionless pulley.

  • Acceleration of system:
    \[
    a = \frac{(m_2 – m_1)g}{m_1 + m_2}
    \]
  • Tension in string:
    \[
    T = \frac{2 m_1 m_2 g}{m_1 + m_2}
    \]

Example 3: Circular Motion

  • Centripetal force:
    \[
    F_c = \frac{mv^2}{r}
    \]

9. Common Problems and Misconceptions

  • Confusing mass with weight:
    \[
    W = mg
    \]
  • Assuming tension is equal in all strings regardless of pulleys.
  • Neglecting normal force variations on inclined planes.
  • Ignoring inertial forces in accelerating frames.

10. Newton’s Laws in Non-Inertial Frames

In accelerating frames, fictitious (pseudo) forces must be added.

\[
If the frame accelerates with ( \vec{a}_{\text{frame}} ), a fictitious force acts:
\]


11. Limitations of Newtonian Mechanics

Newtonian mechanics does not hold when:

  • Speeds approach the speed of light /( (v \rightarrow c) /)
  • Objects are at atomic/subatomic scales (quantum regime)
  • Gravitational fields are extremely strong

These limitations require extensions like:

  • Special Relativity
  • General Relativity
  • Quantum Mechanics

12. Conclusion

Newtonian mechanics provides a coherent and powerful framework to understand motion and force in everyday conditions. Its conceptual clarity and mathematical precision remain essential for students, engineers, and scientists.

Yet, its boundaries are well-known. In moving toward quantum theory and relativity, Newtonian mechanics becomes a limiting case — a gateway through which we learn to question, model, and explore the universe more deeply.

.

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Today in History – 13 May

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Today in History 13 May

Today in History 13 May

1648

Construction of the Red Fort at Dehli was completed.

1857

Sir Ronald Ross, bacteriologist, member of Indian Medical service, Nobel awardee and editor of ‘Science Progress’, was born at Almora, UP.

1949

Maharashtra Granthalay Sangh was established.

1953

The first Indian Navy air station INS Garuda was commissioned at Venduruthy, the naval base in Cochin.

1962

Bharat Ratna, India’s highest award, was given to Dr. Rajendra Prasad (1884-1963).

1962

Dr. Rajendra Prasad (1884-1963) retired from the post of first President.

1962

Dr. Sarvepalli Radhakrishnan (1888-1975) became the second President of India. He held this office till May 13, 1967.

1962

Dr. Zakir Hussain became the Vice President (1962-67).

1967

Dr. Sarvepalli Radhakrishnan (1888-1975) retired from the post of second President.

1967

Dr. Zakhir Hussain became 3rd President of India. He was the first Muslim President of Indian Union. He held this position till August 24, 1969.

1971

General Insurance nationalized.

1994

Renowned environmentalist Maurice F. Strong chosen for the Jawaharlal Nehru International Understanding award for 1992.

1994

Telecom sector opened to private companies under the new national policy announced in Parliament.

1996

M. Karunanidhi (DMK) sworn in as Tamil Nadu CM.

2000

Lara Dutta (21), who said beauty pageants give women a platform to ”voice our choices and opinions”, was named Miss Universe 2000 in the Cyprus capital Nicosia.

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Today in History – 11 May

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Review of Classical Mechanics: Foundations of Motion and Forces

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mechanics motion force

Table of Contents

  1. Introduction
  2. Historical Context and Importance
  3. Kinematics: Describing Motion
  4. Newton’s Laws of Motion
  5. Work, Energy, and Power
  6. Conservation Laws
  7. Rotational Dynamics
  8. Oscillatory Motion and Harmonic Systems
  9. Central Forces and Planetary Motion
  10. Lagrangian and Hamiltonian Mechanics
  11. Limitations of Classical Mechanics
  12. Conclusion

1. Introduction

Classical mechanics is the bedrock upon which modern physics—including quantum mechanics and relativity—is built. It describes the motion of macroscopic objects under the influence of forces and remains accurate for everyday phenomena involving low speeds and large scales.

This review covers the essential ideas and mathematical tools of classical mechanics, serving as a necessary foundation before exploring the non-intuitive realms of quantum physics.


2. Historical Context and Importance

From Aristotle to Newton and beyond, classical mechanics developed through centuries of observation, theory, and experimentation. The Newtonian synthesis in the 17th century transformed it into a predictive, mathematical framework that governed both terrestrial and celestial phenomena.

Classical mechanics:

  • Is deterministic
  • Operates in absolute space and time
  • Serves as the classical limit of more advanced theories

3. Kinematics: Describing Motion

Kinematics deals with motion without considering its cause.

Position, Velocity, and Acceleration

  • Displacement: \( \vec{x}(t) \)
  • Velocity: \( \vec{v}(t) = \frac{d\vec{x}}{dt} \)​
  • Acceleration: \( \vec{a}(t) = \frac{d\vec{v}}{dt} = \frac{d^2\vec{x}}{dt^2} \)

Equations of Uniform Acceleration (1D)

\[ v = v_0 + at \]

\[ x = x_0 + v_0 t + \frac{1}{2} a t^2 \]

\[ v^2 = v_0^2 + 2a(x – x_0) \]

These equations apply under constant acceleration.


4. Newton’s Laws of Motion

First Law (Law of Inertia)

A body remains at rest or in uniform motion unless acted upon by an external force.

Second Law

\[ \vec{F} = m \vec{a} \]

Where:

  • \( vec{F} \) is the net force,
  • m is mass,
  • \[(\vec{a}\) is acceleration.

Third Law

For every action, there is an equal and opposite reaction.

These laws define the interaction between forces and motion.


5. Work, Energy, and Power

Work

\[ W = \int \vec{F} \cdot d\vec{r} \]

Kinetic Energy

\[ K = \frac{1}{2} m v^2 \]

Potential Energy (Conservative Forces)

\[ U = -\int \vec{F} \cdot d\vec{r} \]

Work-Energy Theorem

\[ W_{\text{net}} = \Delta K \]

Power

\[P = \frac{dW}{dt} \]

Energy methods often simplify complex problems involving forces.


6. Conservation Laws

Conservation laws are powerful tools rooted in symmetries (via Noether’s Theorem).

Conservation of Momentum

If \(\vec{F}_{\text{net}} = 0 \), then:

\[ \frac{d\vec{p}}{dt} = 0 \quad \Rightarrow \quad \vec{p} = \text{constant} \]

Where \(\vec{p} = m\vec{v} \)

Conservation of Angular Momentum

\[\vec{L} = \vec{r} \times \vec{p}\]​

\[\frac{d\vec{L}}{dt} = \vec{\tau} \]

If \(\vec{\tau} = 0\), then \(\vec{L}\) is conserved.

Conservation of Energy

In a closed system with conservative forces: \( E = K + U = \text{constant} \)


7. Rotational Dynamics

Rotational motion parallels linear motion:

Angular Displacement, Velocity, Acceleration

\(\theta \), \( \omega = \frac{d\theta}{dt} \)​, \(\alpha = \frac{d\omega}{dt}\)​

Moment of Inertia

\[ I = \sum m_i r_i^2 \quad \text{(discrete)}, \quad I = \int r^2 \, dm \quad \text{(continuous)} \]

Torque

\[\vec{\tau} = \vec{r} \times \vec{F} \]

\[\vec{\tau} = I \alpha \]

Rotational Kinetic Energy

\[ K_{\text{rot}} = \frac{1}{2} I \omega^2\]


8. Oscillatory Motion and Harmonic Systems

Simple Harmonic Motion (SHM)

  • Restoring force: \(F = -kx\)
  • Equation of motion:

\[\frac{d^2x}{dt^2} + \omega^2 x = 0 \]

Solution:

\[x(t) = A \cos(\omega t + \phi)\]

Where:

  • A: amplitude
  • \(\omega = \sqrt{\frac{k}{m}}\)​​: angular frequency
  • \(\phi\): phase constant

Energy in SHM

\[E = K + U = \frac{1}{2} k A^2 = \text{constant} \]


9. Central Forces and Planetary Motion

Newton’s Law of Universal Gravitation

\[F = G \frac{m_1 m_2}{r^2} \]

Orbital Motion

Under inverse-square central force, the motion follows Kepler’s laws. The total mechanical energy: \(E = -\frac{G M m}{2a}\)

Where aaa is the semi-major axis.


10. Lagrangian and Hamiltonian Mechanics

These are reformulations of Newtonian mechanics that are essential in quantum and field theories.

Lagrangian

\[L = T – U\]

Euler-Lagrange Equation

\[\frac{d}{dt} \left( \frac{\partial L}{\partial \dot{q}} \right) – \frac{\partial L}{\partial q} = 0\]

Where qqq is a generalized coordinate.

Hamiltonian

\[H = \sum p_i \dot{q}_i – L\]

Hamilton’s equations:

\[\dot{q}_i = \frac{\partial H}{\partial p_i}, \quad \dot{p}_i = -\frac{\partial H}{\partial q_i}\]

This formulation is pivotal for transitioning into quantum mechanics.


11. Limitations of Classical Mechanics

Despite its successes, classical mechanics has limitations:

  • Fails at relativistic speeds \((v \approx c)\)
  • Cannot explain atomic-scale phenomena
  • Cannot incorporate wave-particle duality
  • Is inherently deterministic, unlike quantum theory

These limitations led to the development of special relativity, quantum mechanics, and quantum field theory.


12. Conclusion

Classical mechanics offers a logically consistent and mathematically elegant description of motion. Its principles—particularly conservation laws and equations of motion—are indispensable in engineering, astronomy, and everyday physics.

However, understanding its boundaries is equally crucial. As we progress into quantum mechanics and beyond, the lessons of classical mechanics will remain deeply embedded in our conceptual and mathematical tools.

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Today in History – 12 May

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today in history 12 may

today in history 12 may

1459

Sun City India founded by Rao in Jodhpur.

1666

Chhatrapati Shivaji Maharaj met Aurangzeb and was arrested.

1780

After a siege that began on April 2, 1780, Americans suffered their worst defeat of the revolution on this day in 1780, with the unconditional surrender of Major General Benjamin Lincoln to British Lieutenant General Sir Henry Clinton and his army of 10,000 at Charleston, South Carolina.

1906

Gandhiji supported the “Home Rule” for India in the name of ”justice and for good of human beings”.

1915

Rash Behari Bose, a revolutionary leader, left India by boarding a Japanese steamer ”Sanuki Maru” under assumed name of P. N. Tagore to dodge the British forces.

1930

Admiral R. H. Tahiliyani, former Navy Chief of India was born.

1937

At London’s Westminster Abbey, George VI and his consort, Lady Elizabeth, were crowned king and queen of the United Kingdom as part of a coronation ceremony that dates back more than a millennium.

1949

S Vijaya Laxmi Pandit, first woman foreign ambassador, was received in US.

1952

Washington welcomed its first female ambassador, India’s Shrimati Vijaya Lakshmi Pandit.

1955

The PM laid the foundation stone for the National Museum.

1966

Sardar Sikandar Hayat, President of Pakistan-occupied Kashmir, resigned.

1984

Dr. Rajah Sir Muthiah Chettiar, social reformer, passed away at Madras.

1987

Britain’s HMS Hermes became Indian Navy’s second aircraft carrier named INS Viraat.

1992

Ms. Santosh Yadav (Indo-Tibetan Border Police) became the second Indian woman to set foot atop Mt. Everest.

1993

Lok Sabha okayed extension of President’s rule in the former BJP-ruled states.

1993

Samsher Bahadur Singh, modern Hindi poet, passed away.

1995

Supreme court stayed Tamil Nadu Governor’s orders allowing Dr. Subramaniam Swamy to prosecute Chief Minister Dr. Jayalalitha under Prevention of Corruption Act.

1997

Prime Ministers of India and Pakistan agreed to set up joint working groups on a range of issues to be identified by Foreign Secretaries.

1998

Bill Clinton, US President, asked India to sign the CTBT.

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