Viscosity

Viscous Forces- These are forces which has tendency to oppose relative motion between different layers of liquid or gases.

Viscosity – Viscosity is the characteristic of a liquid due to which it opposes the relative motion between its various layers.

•    Viscosity is applicable to both liquid and gases.
•    The viscosity of a liquid is because of cohesive forces between layers.
•    Viscosity is liquid is less than viscosity of gases.
•    Solid has no viscosity.

Surface Tension

Cohesive Forces- Cohesive forces are the intermolecular forces, for example; hydrogen bonding and Van der Waals forces which cause a tendency in liquids to resist separation. These forces which are attractive forces exist between molecules of the same material. For example, rain falls as droplets, and not as fine mist, since water has strong cohesion hence its molecules pulls tightly together and droplets are formed. The cohesive force tends to bring closer molecules of a liquid, by making them comparatively large clusters which owes to molecules' dislike for its surrounding.

Floatation

Archimedes' Principle

•    The Archimedes' Principle is named after Archimedes of Syracuse
•    He discovered the law in 212 B.C.
•    The Archimedes' Principle states that any object, wholly or partially immersed in a fluid, is buoyed up by a force equal to the weight of the fluid displaced by the object.

Mathematically, the Archimedes' principle can be stated as Buoyancy = weight of displaced fluid.

Pressure

Pressure- Pressure is defined as force per unit area. The standard unit for pressure is the Pascal (Pa) or Newton per square meter (N/m2).

For an object placed on a surface, the force exerted on the surface by the object is the weight of the object, but in different orientations it might have a different area in contact with the surface and therefore exert a different pressure.

Gravitation

Gravitation – Gravitation oftentimes also termed as Gravity is a force which found among all material objects in the universe. For any two objects or particles having non-zero mass, the force of gravity tends to attract them toward each other. Gravity works on objects of all sizes, be these subatomic particles or clusters of galaxies.

Work, Energy and Power

Work - When a force acts upon an object and displaces it from its original position, it is said that work was done upon the object. There associates three key component to work - force, displacement, and reason or source.

Motion

Scalars - Scalars are quantities that are fully described by a magnitude (or numerical value) alone.

Examples of Scalar Quantities - mass, length, temperature, energy, pressure, volume, electric charge, space-time interval, invariant mass

Vectors - Vectors are quantities that are fully described by both a magnitude and a direction.

Name and Symbols of Different Physical Terms, Descriptions and SI Units

Base quantity	Symbol	Description	SI unit
Length	l	The one dimensional extent of an object.	metre (m)
Matter	m	The amount of matter in an object.

Important Physics Discoveries in Chronology Order

• 1687 - Laws of motion and law of gravity: Newton
• 1782 - Conservation of matter: Lavoisier 
• 1785 - Inverse square law for electric charges confirmed: Coulomb 
• 1801 - Wave theory of light: Young

Inventions, Inventor, Country and Year

• Adrenaline: (isolation of) John Jacob Abel, U.S., 1897.
• Aerosol can: Erik Rotheim, Norway, 1926.
• Air brake: George Westinghouse, U.S., 1868.
• Air conditioning: Willis Carrier, U.S., 1911.