The study of physics covers a wide range of topics, including mechanics, thermodynamics, electromagnetism, optics, atomic and nuclear physics, and relativity. It involves the use of mathematical models and experimental techniques to investigate the behavior of physical systems and to develop new theories and technologies.

1. Contents:
What is Force?
Who discovered Gravitational law?
Discovery of Gravitational Force.
Calculation used by Newton. §
Calculating the constant.
Gravity- A special Case.
Effect of Gravity and its Uses.
Introduction
Sir Isaac newton gave many laws of nature. In his First
law of motion, he described the inherent property of
matters, qualitatively. In his second law, he wrote “A
force action on a body gives it an acceleration which is in
the direction of force and has a magnitude given by ma.”
So, it describes force quantitatively also. In his third law,

2. he describes how force are exerted. Therefore, we can
say he discovered “Force”.
What is force?
The force is an external effort (cause) in the form of a
push or pull which either changes or tends to change the
state of rest or the uniform motion of a body along a
straight line. They are classified into two categories:-
(i) Contact Force. - Frictional force, normal reaction,
tensile force etc.
(ii) Non-Contact Force. - electric, magnetic, gravitational
force.
Who discovered gravitational force?
Sir Isaac Newton (1642-1727)
Perhaps the greatest genius of all time.
Invented the reflecting telescope.
Invented calculus.
Connected gravity and planetary forces.

3.  Philosophiae naturalis.
 Principia mathematical.
Discovery of gravitational force.
In 1665, Isaac Newton performed brilliant
theoretical and experimental tasks in mechanics and
optics. In this year, he focused his attention on the
motion of the moon about the earth. While doing so,
he had a question that what is the force that makes
moon to revolve.
He had data that moon revolves round the earth in
27.3 days. Its distance from earth is R = 3.85 ×10>5
km. The acceleration of moon is, therefore,

4. Displacement and time were converted into SI units.
He had a belief that earth is making the moon to
revolve. But How?
Apple falling incident
Newton was sitting under an apple tree when an apple
fell down from the tree on the earth.
This sparked the idea that the earth attracts all bodies
towards its Centre.
He declared that the laws of nature are same for
earthly and celestial bodies.
Calculation used by Newton
The acceleration of a body falling near the earth’s surface
is about 9.8 m/s2 and moon’s acceleration is 0.0027m/s2
Thus:

8. Characteristics of gravitational force
 Always acts as “Force of Attraction”.
 Form an action-reaction pair.
 Central Forces.
 Independent of the presence of other bodies and
properties of the intervening medium.
 Weakest Force.
Definition:
The force of attraction between any two material
particles is directly proportional to the product of the
masses of the particles and inversely proportional to the
square of the distance between them. It acts along the
line joining the two particles.
i.e.

9. Gravity-A special case:
Gravity is the force by which earth attracts a body
towards its center.
Where,
– Fe = forces of attraction between Earth and particle of
mass m.
– Me = mass of Earth.
– m = mass of particle.
– Re = distance between the centers of the Earth and
particle.
– G = Universal gravitational constant.
Gravity on earth
 Follows Newton's Law of Universal Gravitation
 By Newton’s second law, F = mg 
Compare with F = mg so g = GM/r2

10.  g depends inversely on the square of the distance
 g depends on the mass of the planet
 Nominally, g = 9.81 m/s2 or 32.2 ft/s2
• At the equator g = 9.78 m/s2
• -At the North pole g = 9.83 m/s2
• g on the Moon is 1/6 of g on Earth.
Uses of Gravity
 Provides necessary centripetal force to moon to
revolve.
 Provides force to Satellites to revolve round the earth.
 To make the bodies fall from height.
 Formation of Tides in the ocean.

21. Waves.

38. END.

39. Laws of Thermodynamics
Thermodynamics
• Thermodynamics is the study of the effects of work, heat, and
energy on a system
• Thermodynamics is only concerned with macroscopic (large-scale)
changes and observations
• All of thermodynamics can be expressed in terms of four
quantities
• Temperature (T)
• Internal Energy (U)
• Entropy (S)
• Heat (Q)
• These quantities will be defined as we progress through the
lesson
Classical vs Statistical
• Classical thermodynamics concerns the relationships between
bulk properties of matter. Nothing is examined at the atomic or
molecular level.
• Statistical thermodynamics seeks to explain those bulk properties
in terms of constituent atoms. The statistical part treats the
aggregation of atoms, not the behavior of any individual atom.

40. 1.0 You can’t win (1st
law)
• The first law of thermodynamics is an extension of the law of
conservation of energy
• The change in internal energy of a system is equal to the heat
added to the system minus the work done by the system
ΔU = Q - W

41. 1.1 Process Terminology
• Adiabatic – no heat transferred
• Isothermal – constant temperature
• Isobaric – constant pressure
• Isochoric – constant volume
1.2 Heat Capacity
• The amount of heat required to raise a certain mass of a material
by a certain temperature is called heat capacity.
Q = mcxΔT
The constant cx is called the specific heat of substance x, (SI units of
J/kg·K
1.2.1 Heat Capacity of Ideal Gas
• CV = heat capacity at constant volume
CV = 3/2 R
• CP = heat capacity at constant pressure
CP = 5/2 R
• For constant volume
Q = nCVΔT = ΔU
• The universal gas constant R = 8.314 J/mol·K

42. 2.0 You can’t break even (2nd
Law)
• Think about what it means to not “break even”. Every effort you
put forth, no matter how efficient you are, will have a tiny bit of
waste.
• The 2nd
Law can also be stated that heat flows spontaneously
from a hot object to a cold object (spontaneously means without
the assistance of external work)