Physics Module 3 .pdf on nanotechnology1

**Classical Mechanics: A Detailed Overview**

**Classical mechanics**, also known as Newtonian mechanics, is a branch of physics that deals with the motion of objects and the forces acting upon them. It is one of the most foundational areas of physics, primarily developed by Sir Isaac Newton in the 17th century. Though its principles have been superseded in certain domains by quantum mechanics and relativity, classical mechanics remains crucial for understanding the macroscopic world and serves as the bedrock for many modern physical theories.

In this comprehensive exploration of classical mechanics, we will cover key principles, laws, mathematical frameworks, and its applications in different fields of science and engineering.

### Historical Context and Development

Classical mechanics began with the works of early scientists like Galileo Galilei, who studied the motion of objects under gravity. However, it was **Isaac Newton** who unified the ideas of motion and force with his three **Laws of Motion** and the **Law of Universal Gravitation**. His seminal work, *Philosophiæ Naturalis Principia Mathematica* (1687), laid the foundation for understanding the motion of bodies under the influence of forces.

The theory of classical mechanics was expanded by many later scientists, including **Joseph-Louis Lagrange** and **William Rowan Hamilton**, who reformulated Newton’s equations into more abstract and mathematically elegant frameworks: **Lagrangian mechanics** and **Hamiltonian mechanics**. These developments were instrumental in extending the reach of classical mechanics to fields like celestial mechanics, fluid dynamics, and rigid body motion.

### Core Concepts in Classical Mechanics

#### 1. **Newton's Laws of Motion**
The three **Laws of Motion**, formulated by Newton, are the foundation of classical mechanics.

- **First Law (Law of Inertia)**: An object at rest will stay at rest, and an object in motion will stay in motion with the same speed and direction unless acted upon by a net external force. This law introduces the concept of inertia, which is the resistance of an object to changes in its state of motion.

- **Second Law (F = ma)**: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This law provides the quantitative relationship between force, mass, and acceleration. Mathematically, it is expressed as:

\[
F = ma
\]
where \( F \) is the force acting on the object, \( m \) is the mass, and \( a \) is the acceleration.

- **Third Law (Action and Reaction)**: For every action, there is an equal and opposite reaction. This means that forces always occur in pairs; if object A exerts a force on object B, object B will exert an equal and opposite force on object A.

#### 2. **Kinematics**
Kinematics is the study of the motion of objects without considering the forces that cause the motion. It involves quantities like displacement, velocity, and

1. Nano

2. Nanotechnology the beginning
The lycargus cup

3. Nanotechnology the beginning
Damascus Sword

4. There is plenty of room at the bottom-
Richard P Feynman- The Actual
beginning
•The fact that enormous amounts of information can be
carried in an exceedingly small space – is, of course, well
known to the biologists, and resolves the mystery which
existed before we understood all this clearly, of how it
could be that, in the tiniest cell, all of the information for
the organization of a complex creature such as ourselves
can be stored. All this information – whether we have
brown eyes, or whether we think at all, or that in the
embryo the jawbone should first develop with a little hole
in the side so that later a nerve can grow through it – all
this information is contained in a very tiny fraction of the
cell in the form of long-chain DNA molecules in which
approximately 50 atoms are used for one bit of information
about the cell.

5. Moore’s Law - the actual beginning

6. Manipulated 35 individual xenon
atoms to spell out the IBM logo- the
realization

7. Carbon nanotubes- the realization

8. Questions
•How big is ‘nano’?
•How big is a nanometre?
•What is a nanoscience?
•What is a nanotechnology?
•Why nano?

10. An Interdisciplinary Endeavor
Nanoscience
& Nanotechnology
Engineering
Medicine
Biotechnology
Biology Chemistry Physics
Information Technology
Materials Science

11. Surface Areas at the Nanoscale
http://www.nano.gov/nanotech-101/special
1 mm cubes 1 cm cubes 1 nm cubes

12. How Surface Area Scales (Changes)
12
For a fixed total
volume, decreasing
the radius by a factor
of two doubles the
surface
Crushing a 1cm
particle into nano
particles increases the
surface area
thousands of times!

13. How Surface Area Scales Changes
13
nano

17. Applications
•These are used in transistors, solar cells, diode
lasers, LEDs, etc.
•These may increase the efficiency of silicon
photovoltaic cells.
• These are also significant for optical applications
like amplifiers, biological sensors, etc.
•These are used as photocatalysts.
•They have potential applications in spectroscopy
and fluorescent biomedical imaging.

19. Applications
•They are useful in digital computing.
•These are used for the preparation of active
electronic components like p-n junction, logic
gates, etc.
•They have potential applications in high-
density data storage.
• Silver chloride nanowires are used as
photocatalysts to decompose organic
molecules in polluted water.

22. NANOCLUSTURE