Topics
Gravitation
- Concept of Gravitation
- Force
- Motion and Rest
- Centripetal Acceleration and Centripetal Force
- Kepler’s Laws
- Newton’s Universal Law of Gravitation
- Uniform Circular Motion (UCM)
- Earth’s Gravitational force
- Acceleration Due to Gravity (Earth’s Gravitational Acceleration)
- Concept of Mass and Weight
- Gravitational Waves
- Free Fall
- Gravitational Potential Energy
- Weightlessness in Space
Periodic Classification of Elements
- History of Periodic Table: Early Attempts at the Classification of Elements
- Dobereiner’s Triads
- Newland's Law of Octaves
- Mendeleev’s Periodic Table
- Merits and Demerits of Mendeleev’s Periodic Table
- Modern Periodic Law
- The Modern Periodic Table
- Structure of the Modern Periodic Table
- Modern Periodic Table and Electronic Configuration of Elements
- Groups and Electronic Configuration
- Periods and Electronic Configuration
- Periodic Properties
- Valency
- Atomic Radius Or Atomic Size
- Metallic and Non-metallic Characters
- Group VIIA Or Group 17 (The Halogens)
Chemical Reactions and Equations
- Chemical Reaction
- Chemical Equation
- Balancing Chemical Equation
- Types of Chemical Change or Chemical Reaction
- Direct Combination (or Synthesis) Reaction
- Decomposition Reactions
- Single Displacement Reactions
- Double Displacement Reaction
- Energy Change in Chemical Reactions
- Rate of Chemical Reaction
- Factors Affecting the Rate of a Chemical Reaction
- Oxidation, Reduction and Redox Reactions
- Corrosion of Metals
- Rancidity of Food and Its Prevention
Effects of Electric Current
- Electric Circuit
- Ohm's Law (V = IR)
- Heating Effect of Electric Current
- Magnetic Effect of Electric Current
- Right-hand Thumb Rule
- Magnetic Field Due to Current in a Loop (Or Circular Coil)
- Magnetic Field Due to a Current Carving Cylindrical Coil (or Solenoid)
- Force on a Current Carrying Conductor in a Magnetic Field
- Fleming’s Left Hand Rule
- Electric Motor
- Electromagnetic Induction
- Galvanometer
- Fleming’s Right Hand Rule
- Types of Current
- Electric Generator
Heat
Refraction of Light
Lenses
- Concept of Lenses
- Spherical Lens
- Convex Lens
- Images Formed by Convex Lenses
- Concave Lens
- Images Formed by Concave Lenses
- Sign Convention
- Lens Formula
- Magnification Due to Spherical Lenses
- Power of a Lens
- Combination of Lenses
- Human Eye
- Working of the Human Eye
- Eye Defect and Its Correction: Myopia Or Near-sightedness
- Eye Defect and its Correction: Hypermetropia or Far-sightedness
- Eye Defect and Its Correction: Presbyopia
- Persistence of Vision
Metallurgy
- Types of Element: Metals
- Physical Properties of Metals
- Chemical Properties of Metal
- Reactions of Metal
- Reactivity Series of Metals
- Types of Element: Non-metal
- Physical Properties of Non-metal
- Chemical Properties of Non-metal
- Ionic Compounds
- Metallurgy
- Basic Principles of Metallurgy
- Extraction of Reactive Metals
- Extraction of Aluminium
- Extraction of Moderately Reactive Metals
- Extraction of Less Reactive Metals
- Refining of Metals
- Corrosion of Metals
- Prevention of Corrosion
Carbon Compounds
- Carbon Compounds in Everyday Life
- Bonds in Carbon Compounds
- Carbon: a Versatile Element
- Properties of Carbon
- Hydrocarbons
- Structural Variations of Carbon Chains in Hydrocarbons
- Functional Groups in Carbon Compounds
- Homologous Series of Carbon Compound
- Nomenclature of Organic Compounds
- The IUPAC System of Nomenclature
- Chemical Properties of Carbon Compounds
- Ethanol
- Ethanoic Acid
- Macromolecules and Polymers
Space Missions
- Concept of Space Missions
- Artificial Satellites
- Types of Satellite
- Orbits of Artificial Satellites
- Space launch technology
- Space Missions Away from Earth
- India’s Space Programmes: Chandrayaan – 1
- India’s Space Programmes: Chandrayaan – 2
- India’s Space Programmes: Chandrayaan – 3
- India’s Space Programmes: Mangalyaan (Mars vehicle)
- India’s Space Programmes: Missions to Other Planets
- India and Space Technology
- Space Debris and Its Management
School of Elements
The Magic of Chemical Reactions
The Acid Base Chemistry
- Properties of Acids
- Strength of Acidic or Basic Solutions
- Strength of Acidic or Basic Solutions
- Acids, Bases and Their Reactivity
- Acid or a Base in a Water Solution
- Preparation and Uses of Baking Soda
- Preparation and Uses of Bleaching Powder
- Preparation and Uses of Washing Soda
- Preparation and Uses of Plaster of Paris
- Chemicals from Common Salt - Soap as a Salt
The Electric Spark
All about Electromagnetism
- Magnetic Force
- The Bar Magnet
- Right-hand Thumb Rule
- Magnetic Field Due to Current in a Loop (Or Circular Coil)
- Magnetic Field Due to a Current Carving Cylindrical Coil (or Solenoid)
- Force on a Current Carrying Conductor in a Magnetic Field
- Electric Motor
- Electromagnetic Induction
- Alternating Current (A.C.) Generator
- Direct Current Motor
- Household Electrical Circuits
Wonders of Light 1
- Spherical Mirrors
- Concave Mirror
- Concave Mirror
- Sign Convention
- Linear Magnification (M) Due to Spherical Mirrors
- Images Formed by Sperical Lenses
- Convex Lens
- Sign Convention
- Magnification Due to Spherical Lenses
- Power of a Lens
- Human Eye
- Eye Defect and Its Correction: Myopia Or Near-sightedness
- Spherical Mirrors
Wonders of Light 2
Striving for better Environment 1
- Pollution and Its Types
- Air Pollution and Its Causes
- Effects of Air Pollution
- Water Pollution and Its Causes
- Effects of Water Pollution
- Soil Pollution and its Causes
- Effects of Soil Pollution
- Noise Pollution
- Radioactive Pollution and Effects
- Abatement of Pollution
- Sustainable Use of Resources
- Mass and Weight
- Difference Between Mass and Weight
Mass and Weight:
1. Mass: It is the amount of matter in an object. It is related to inertia, which is the resistance of an object to change its state (whether at rest or moving). According to Newton’s first law, it is the measure of the inertia of an object. The greater the mass, the greater the inertia.
- Mass is a scalar quantity, meaning it only has magnitude, not direction. Mass does not change from one place to another; it stays the same everywhere.
- The SI unit of mass is kg. When using a two-pan balance in a shop, we are comparing the mass of two objects.
2. Weight: It is the gravitational force that the Earth exerts on an object. It depends on the mass of the object and gravity. Its S.I. unit is Newton.
- Weight is a vector quantity, meaning it has both magnitude and direction (towards the Earth’s centre).
- Weight can change from place to place, depending on the strength of gravity (for example, at different heights or on other planets). What we commonly measure in grams or kilograms is actually mass, not weight.
W = F = m × g .......( `g = (GM)/(R^2)`)
The weight of an object can change from one place to another, from one planet to another.
The weight of an object on the moon is given by the formula.
`"W"_"m" ="GM"_"m" xx "m"/"R"_"m"^2`
- Wm= weight of an object on moon
- Mm= mass of the moon = 7.36 × 1022
- Rm= radius of the moon = 1.74 × 106
- G = Universal Gravitational Constant = 6.67 × 10⁻¹¹ Nm2/kg2
- m = Mass of the object
Substituting the values:
`therefore` `"W"_"m" = (6.67 × 10⁻¹¹ xx 7.36 xx 10^22 xx"m")/((1.74 xx 10^6"m")^2)`
`"W"_"m" = 2.431 xx 10^10 "Gm"`
Similarly, the weight of the object on Earth is:
`"W"_"e" = 1.474 xx 10^11 "Gm"`
Taking the ratio:
`therefore` `"W"_"m"/"W"_"e" = ("Weight of object on Moon")/("Weight of object on Earth") = (2.431xx10^10"Gm")/(1.474 xx 10^11"Gm")= 1/6`
`therefore` Weight of an object on the moon is `1/6`th the weight of an object on the earth.
Difference Between Mass and Weight:
| Aspect | Mass | Weight |
|---|---|---|
| Definition | Amount of matter in an object | Force exerted by gravity on an object’s mass |
| Symbol | m | W |
| SI Unit | Kilogram (kg) | Newton (N) |
| Measured With | Balance scale or beam balance | Spring balance |
| Depends On | Quantity of matter | Mass and gravitational acceleration (W = mg) |
| Varies with Location? | No | Yes |
| Constant on Earth & Moon? | Yes | No (less on Moon, more on planets with higher gravity) |
| Type of Quantity | Scalar | Vector (has direction towards the centre of gravity) |
| Can it be Zero? | No | Yes (in space or zero-gravity environment) |
| Example (Rajeev) | 75 kg (remains same everywhere) | 735 N on Earth (75 × 9.8), ~123 N on Moon |
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