# Chapter 5 – Heat and Energy

The following Topics and Sub-Topics are covered in this chapter and are available on MSVgo:

Introduction

“Heat” and “Energy” must be familiar terms for you. Even in your daily life, you must be using these terms quite often. You might have experienced in the summer season that your mother suggests you consume glucose water to maintain your energy even in the increased heat. Did you get an idea of how these two terms are interrelated?

A form of energy that is transferred between objects or systems with different temperatures is called heat. Energy, be it in any form, is always associated with a motion. You might have experienced how heat is generated when you rub your hands for a while. Let us now dig into the concepts of heat and energy.

#### Concepts Of Heat And Temperature

Heat: Heat is a form of energy produced due to the random motion of molecules constituting the body. Heat is measured in terms of its S.I. unit – joule (J). Heat also has other units like calorie (cal) and kilocalorie (kcal). Joule and calorie are related to each other as follows:

1 cal = 4.186 J ~ 4.2 J

Temperature: A quantity that tells about the thermal state of the body is called Temperature. Temperature also helps determine the direction of heat flow when two bodies having different temperatures are placed in contact. Temperature is measured in terms of its S.I. unit – kelvin (K). The most commonly used unit of temperature is degree Celsius (0C). Kelvin and degree celsius are related to each other as follows:

Tk = 273 + t0C

#### Anomalous Expansion Of Water

You must have seen that substances expand when they are being heated. This happens because the density decreases when materials are heated and vice versa when cooled down. Let us now consider the case of water.

Generally, cold water remains unchanged until 40C. As we cool the water, its density gradually increases. As it reaches 4oC, the density reaches its maximum point. What happens next is quite surprising. If you try to cool the water further, to turn it into ice (00C), water will expand and drop its temperature. That is, the density of water will decrease when you cool it down from 40C to 00C. This is called the anomalous expansion of water.

#### Global Warming and the Greenhouse Effect

Global warming is a gradual increase in Earth’s temperature, usually due to the greenhouse effect, which results from increased levels of CFCs, carbon dioxide, and other pollutants. A phenomenon like global warming has changed the climatic pattern of the earth.

There are a few causes of this phenomenon that harms plants, animals, and humans. The causes of global warming are classified as human-made and natural.

1. Man-made causes: Deforestation, chlorofluorocarbon, vehicles, agriculture, industrial development, overpopulation, etc.
2. Natural Cause: Water vapour, volcanoes, forest blazes, melting permafrost, etc.

The Greenhouse Effect is one of the reasons which leads to global warming. Understanding the greenhouse effect is equally important because global warming and greenhouse effects are related to each other. In a greenhouse, the plants require a warm temperature to grow.

A greenhouse is almost entirely made up of glass. Hence, the heat is retained, which helps the plants to thrive. The temperature in the greenhouse gets higher than the temperature outside the greenhouse. This is called the greenhouse effect.

#### Law of Thermodynamics

Thermodynamics deals with the movement of energy from one form to another form. It gives the relationship between temperature and heat with work done and energy. Given below are the laws of thermodynamics:

1. The first law of thermodynamics: This law is associated with the law of conservation of energy. It states that energy is always conserved. It can neither be created nor destroyed but can be transferred from one form to another form.
2. The second law of thermodynamics:  There exists a useful state variable called entropy S. The change in entropy delta S is equal to the heat transfer delta Q divided by the temperature T.
3. Third law of thermodynamics: At absolute zero, the entropy of a perfect crystal is zero.
4. Zeroth Law: If both the two systems are in thermal equilibrium with a third system, then all three of them are in thermal equilibrium with each other.

#### Energy Sources

The energy sources can be commercial or non-commercial.

• Commercial entities usually consume commercial energy. It is accessible to the consumers at a price to be paid. It is a non-renewable source of energy. It is usually not used by households and residents. Commercial sources like electricity, coal, and petroleum are bought and sold to users.
• Non-commercial energy is used for household purposes by people and is available free of cost. It marks the standard of living of a country. Example: firewood, cow dung, agricultural waste, etc.

#### Renewable Versus Non-Renewable Sources Of Energy

 Renewable Sources Of Energy Non-Renewable Sources Of Energy The resources which can be renewed are called renewable sources of energy. The resources which cannot be renewed once consumed are called non-renewable sources of energy. These resources do not harm the environment in terms of pollution. These resources create pollution and harm the environment. These resources are inexhaustible. These resources are exhaustible. These resources do not get affected by any kind of human activity. These resources get affected by human activity. Example: Water, Air, Solar energy. Example: Oil, Mineral, Coal.

#### FAQs

1. What is heat and its S.I. unit?
A: Heat is a form of energy produced due to the random motion of molecules constituting the body. Heat is measured in terms of its S.I. unit – joule (J).
2. Which substances expand when heated? Give examples.
A: Iron and brass are two examples of substances that expand on heating.
3. What is a system in thermodynamics?
A: It is a body of ration or/and matter, confined in space by the walls. It separated from the surroundings with defined permeabilities.
4. Is the sun renewable or non-renewable energy?
A: Sun is renewable energy.
5. What is an anomalous expansion of water?
A: The expansion of water when it cooled down from 4oC to 0oC is the anomalous expansion of water.

We have learned all the essential concepts of Heat and Energy. To understand this topic in detail, you can refer to the video library by downloading the MSVgo app from the Google Play Store, iOS App Store, or browse the MSVgo website.

### High School Physics

• Alternating Current
• Atoms
• Communication Systems
• Current Electricity
• Dual nature of Radiation and Matter
• Electric Charges and Fields
• Electricity
• Electromagnetic Induction
• Electromagnetic Waves
• Electrons and Photons
• Electrostatic Potential and Capacitance
• Fluid Pressure
• Force and Acceleration
• Force And Laws Of Motion
• Gravitation
• Internal Energy
• Kinetic Theory
• Law of motion
• Light – Reflection And Refraction
• Magnetic Effects Of Electric Current
• Magnetism and Matter
• Management Of Natural Resources
• Mechanical properties of Fluids
• Mechanical properties of Solids
• Motion
• Motion in a plane
• Motion in a straight line
• Moving Charges and Magnetism
• Nuclear Energy
• Nuclei
• Oscillations
• Our Environment
• Paths of Heat
• Physical world
• Ray optics and optical instruments
• Semiconductor Devices
• Semiconductor Electronics: Materials, Devices and Simple Circuits
• Simple Machines
• Sound
• Sources Of Energy
• Specific and Latent Heats
• Spherical Mirrors
• Static Electricity
• Systems of Particles and Rotational motion
• Thermal properties of matter
• Thermodynamics
• Units and Measurement
• Vectors, Scalar Quantities and Elementary Calculus
• Wave Optics
• Waves
• Work, Power and Energy

### High School Chemistry

• Acids, Bases and Salts
• Alcohols, Phenols and Ethers
• Aldehydes, Ketones and Carboxylic Acids
• Aliphatic and Aromatic Hydrocarbons
• Alkyl and Aryl Halides
• Amines
• Analytical Chemistry
• Atomic Structure
• Atoms And Molecules
• Basic concepts of Chemistry
• Biomolecules
• Carbon And Its Compounds
• Carboxylic acids and Acid Derivatives
• Chemical Bonding and Molecular Structures
• Chemical Energetics
• Chemical Equilibria
• Chemical Kinetics
• Chemical Reactions And Equations
• Chemical Reactions and Their Mechanisms
• Chemistry in Everyday Life
• Chemistry of p-Block elements
• Chemistry of Transition and Inner Transition
• Classification of Elements
• Coordination Compounds
• Cyanide, Isocyanide, Nitro compounds and Amines
• Electrochemistry
• Electrolysis
• Elements, Compounds and Mixtures
• Environmental Chemistry
• Equilibrium
• Ethers and Carbonyl compounds
• Haloalkanes and Haloarenes
• Hydrocarbons
• Hydrogen
• Ideal solutions
• Introduction to Organic Chemistry
• Ionic equilibria
• Matter
• Matter Around Us
• Matter In Our Surroundings
• Metallurgy
• Metals And Non-Metals
• Mole Concept and Stoichiometry
• Natural Resources
• Organic Chemistry – Basic Principles
• Periodic Classification of Elements
• Physical and Chemical Changes
• Physical and Chemical Properties of Water
• Polymers
• Preparation, Properties and Uses of Compounds
• Principles and Processes of Isolation of Elements
• Redox Reactions
• Relative Molecular Mass and Mole
• States of Matter
• Structure Of The Atom
• Study of Compounds
• Study of Gas Laws
• Study of Representative Elements
• Surface Chemistry
• The d-block and f-block elements
• The Gaseous State
• The p-Block Elements
• The Periodic Table
• The s-Block Elements
• The Solid State
• Thermodynamics

### High School Biology

• Absorption and Movement of Water in Plants
• Anatomy of Flowering Plants
• Animal Kingdom
• Bacteria and Fungi-Friends and Foe
• Biodiversity and Conservation
• Biofertilizers
• Biological Classification
• Biomedical Engineering
• Biomolecules
• Biotechnology and its Applications
• Biotic Community
• Body Fluids and Circulation
• Breathing and Exchange of Gases
• Cell – Unit of Life
• Cell Cycle and Cell Division
• Cell Division and Structure of Chromosomes
• Cell Reproduction
• Cellular Respiration
• Chemical Coordination and Integration
• Circulation
• Control And Coordination
• Crop Improvement
• Digestion and Absorption
• Diversity In Living Organisms
• Ecosystem
• Environmental Issues
• Excretory Products and their Elimination
• Flowering Plants
• Genes and Chromosomes
• Health and Diseases
• Health and Its Significance
• Heredity And Evolution
• Heredity and Variation
• How Do Organisms Reproduce?
• Human Diseases
• Human Eye And Colourful World
• Human Health and Disease
• Human Population
• Human Reproduction
• Hygiene
• Improvement In Food Resources
• Integumentary System- Skin
• Kingdom Fungi
• Kingdom Monera
• Kingdom Protista
• Life Processes
• Locomotion and Movement
• Microbes in Human Welfare
• Mineral Nutrition
• Molecular Basis of Inheritance
• Morphology of Flowering Plants
• Neural Control And Coordination
• Nutrition in Human Beings
• Organism and Population
• Photosynthesis
• Photosynthesis in Higher Plants
• Plant Growth and Development
• Plant Kingdom
• Pollination and Fertilization
• Pollution; Sources and its effects
• Principles of Inheritance and Variation
• Reproduction and Development in Angiosperms
• Reproduction in Organisms
• Reproductive Health
• Respiration in Human Beings
• Respiration in Plants
• Respiratory System
• Sexual Reproduction in Flowering Plants
• Strategies for Enhancement in Food Production
• Structural Organisation in Animals
• Structural Organisation of the Cell
• The Endocrine System
• The Fundamental Unit Of Life
• The Living World
• The Nervous System and Sense Organs
• Tissues
• Transpiration
• Transport in Plants

### High School Math

• Algebra – Arithmatic Progressions
• Algebra – Complex Numbers and Quadratic Equations
• Algebra – Linear Inequalities
• Algebra – Pair of Linear Equations in Two Variables
• Algebra – Polynomials
• Algebra – Principle of Mathematical Induction
• Binomial Theorem
• Calculus – Applications of Derivatives
• Calculus – Applications of the Integrals
• Calculus – Continuity and Differentiability
• Calculus – Differential Equations
• Calculus – Integrals
• Geometry – Area
• Geometry – Circles
• Geometry – Conic Sections
• Geometry – Constructions
• Geometry – Introduction to Euclid’s Geometry
• Geometry – Three-dimensional Geometry
• Geometry – Lines and Angles
• Geometry – Straight Lines
• Geometry – Triangles
• Linear Programming
• Matrices and Determinants
• Mensuration – Areas
• Mensuration – Surface Areas and Volumes
• Number Systems
• Number Systems – Real Numbers
• Permutations and Combinations
• Probability
• Sequence and Series
• Sets and Functions
• Statistics
• Trignometry – Height and Distance
• Trignometry – Identities
• Trignometry – Introduction

### Middle School Science

• Acids, Bases And Salts
• Air and Its Constituents
• Basic Biology
• Body Movements
• Carbon and Its Compounds
• Cell – Structure And Functions
• Changes Around Us
• Chemical Effects Of Electric Current
• Coal And Petroleum
• Combustion And Flame
• Components Of Food
• Conservation Of Plants And Animals
• Crop Production And Management
• Electric Current And Its Effects
• Electricity And Circuits
• Elements and Compounds
• Fibre To Fabric
• Food production and management
• Force And Pressure
• Forests: Our Lifeline
• Friction
• Fun With Magnets
• Garbage In, Garbage Out
• Getting To Know Plants
• Health and Hygiene
• Heat
• Hydrogen
• Life Processes: Nutrition in Animals and Plants
• Materials: Metals And Non-Metals
• Matter and Its States
• Metals and Non-metals
• Micro Organisms: Friend And Foe
• Motion And Measurement Of Distances
• Motion And Time
• Nutrition In Animals
• Nutrition In Plants
• Organization in Living Things
• Our Environment
• Physical And Chemical Changes
• Pollution and conservation
• Pollution Of Air And Water
• Reaching The Age Of Adolescence
• Reproduction In Animals
• Reproduction In Plants
• Respiration In Organisms
• Rocks and Minerals
• Separation Of Substances
• Simple Machines
• Soil
• Some Natural Phenomena
• Sorting Materials Into Groups
• Sound
• Stars And The Solar System
• Structure of Atom
• Synthetic Fibers And Plastics
• The Living Organisms And Their Surroundings
• Transfer of Heat
• Transformation of Substances
• Transportation In Animals And Plants
• Universe
• Waste-water Story
• Water: A Precious Resource
• Weather, Climate And Adaptations Of Animals To Climate
• Winds, Storms And Cyclones

### Middle School Math

• Area and Its Boundary
• Boxes and Sketches
• Data Handling
• Fun With Numbers
• Heavy and Light
• How Many
• Long And Short
• Mapping
• Measurement
• Money
• Multiplication and Factors
• Multiply and Divide
• Numbers
• Parts and Wholes
• Pattern Recognition
• Patterns
• Play With Patterns
• Rupees And Paise
• Shapes And Angles
• Shapes And Designs
• Shapes and Space
• Similarity
• Smart Charts
• Squares
• Subtraction
• Tables And Shares
• Tenths and Hundredths
• Time