Presentation 1.pdf
- 1. 𝑺𝒖𝒃𝒎𝒊𝒕𝒕𝒆𝒅 𝒃𝒚-𝑨𝒏𝒖𝒑 𝑹𝒂𝒏𝒋𝒂𝒏 𝑺𝒐𝒓𝒆𝒏𝒈 𝑪𝒍𝒂𝒔𝒔-𝑰𝑿'𝑨' 𝑹𝒐𝒍𝒍 𝑵𝒐-𝟎𝟔 𝑺𝒖𝒃𝒋𝒆𝒄𝒕-𝑷𝒉𝒚𝒔𝒊𝒄𝒔 𝑺𝒖𝒃𝒎𝒊𝒕𝒕𝒆𝒅 𝑻𝒐-𝑻𝒓 𝑩𝒊𝒔𝒉𝒏𝒖𝒑𝒓𝒊𝒚𝒂 𝑩𝒉𝒐𝒍
- 3. HEAT AND TEMPERATURE Basis of Comparison Heat Temperature Meaning It refers to the amount of energy present in a body It is the measure of the heat’s intensity Unit of Measurement Joules Celsius, Fahrenheit, Kelvin Measures It is the total kinetic and potentialenergy which the molecules in an object contain It is the average kinetic energy of the molecules present in an object Working Ability The heat has the ability to do work We can use it to measure the degree of heat Device Calorimeter Thermometer Symbol Q T Property It flows from a hotter object to a cooler object It rises when we heat it and falls when we cool it
- 4. HEAT Heat is the thermal energy transferred between systemsdue to a temperature difference.In colloquial use, heat sometimes refers to thermal energy itself. Thermal energy is the kinetic energy of vibrating and colliding atoms in a substance. An example of formal vs. informal usage may be obtained from the right-hand photo, in which the metal bar is "conducting heat" from its hot end to its cold end, but if the metal bar is considered a thermodynamic system, then the energy flowing within the metal bar is called internal energy, not heat. The hot metal bar is also transferring heat to its surroundings, a correct statementfor both the strict and loose meanings of heat. Another example of informal usage is the term heat content, used despite the fact that physics defines heat as energy transfer. More accurately, it is thermal energy that is contained in the system or body, as it is stored in the microscopic degrees of freedom of the modes of vibration. Heat is energy in transfer to or from a thermodynamic system, bya mechanism that involves the microscopic atomic modes of motion or the corresponding macroscopic properties.This descriptive characterization excludes the transfers of energy by thermodynamic work or mass transfer. Defined quantitatively, the heat involved in a process is the difference in internal energy between the final and initial states of a system, and subtracting the work done in the process.This is the formulation of the first law of thermodynamics. The measurement of energy transferred as heat is called calorimetry, performed by measuring its effect on the states of interacting bodies. For example, heat can be measured by the amount of ice melted, or by change in temperature of a body in the surroundings of the system.
- 5. Heat TransferOccurs by Three Mechanisms Conduction: It is the method in which the transfer of heat takes place between atomsand molecules in direct contact. Convection: It is the method in which the transfer of heat happensby the movement of the heated substance. Radiation:It is the method in which the transfer of heat takes place by electromagnetic waves. Classificationof Heat Heat can be classified as follows: • Hot • Cold Hot Objects with high heat content are defined as hot (Hotness or coolness of an object is a relative term is always measured with respect to a reference object). Examples of hot objects aroundus includethe sun, fire, hot pans, air from a hairdryer, lavafrom volcaniceruptions, etc. Cold Objects with lower heat content are defined as cold objects. Hotness or coolnessof an object is a relativeterm that is always measured with respect to a reference object. Examples of cold objects around us include ice, air from an air conditioner,cold drinks, metal vessels kept in open on cold winter daysetc. Sources of Heat There are many sources of heat, but the following are the main sources of heat: • Sun • Chemical • Electrical • Nuclear
- 6. TEMPERATURE Temperature is a physical quantity that expresses quantitatively the attribute of hotness or coldness. Temperature is measured with a thermometer.It reflects the kinetic energy of the vibrating and colliding atoms making up a substance. Thermometers are calibrated in various temperature scales that historically have relied on various reference points and thermometric substancesfor definition. The most common scales are the Celsius scale with the unit symbol °C (formerly called centigrade), the Fahrenheit scale (°F), and the Kelvin scale (K), the latter being used predominantly for scientific purposes. The kelvin is one of the seven base units in the International System of Units (SI). Absolute zero, i.e., zero kelvin or −273.15 °C, is the lowest point in the thermodynamic temperature scale. Experimentally, it can be approached very closely but not actually reached, as recognized in the third law of thermodynamics. It would be impossible to extract energy as heat from a body at that temperature. Temperature is important in all fields of natural science, including physics, chemistry, Earth science, astronomy, medicine, biology, ecology, material science, metallurgy, mechanical engineering and geography as well as most aspects of daily life.
- 7. Relationship between Temperature and Kinetic Energy Kinetic energy is the energy possessed by a body due to its motion. We see a range of kinetic energy in molecules because all molecules don’t move at the same speed. When a substance absorbs heat, the particles move faster, so the average kinetic energy and therefore the temperature increases. As stated in the kinetic-molecular theory, the temperature of a substance is related to the average kinetic energy of the particles of that substance.When a substanceis heated, some absorbed energy is stored within the particles, while some energy increases the motion of the particles. This is registered as an increase in the temperature of the substance. Solids, liquids, and gases all have a temperature. The particles within a solid don’t move, but they have vibrational motion. The temperature increases when molecules vibrate faster. The melting point of a solid is the temperature at which the vibrational motion overcomes the forces of attraction holding the molecules in a solid formation.
- 8. What is Thermal Expansion Thermal expansion is the phenomenon observed in solids, liquids, and gases. In this process, an object or body expands on the application of heat (temperature). Thermal expansion defines the tendency of an object to change its dimension either in length, density, area, or volume due to heat. When the substanceis heated it increases its kinetic energy. Thermal expansion is of three types: • Linear expansion • Area expansion • Volume expansion The relative expansion of the material divided by the change in temperature is known as the coefficient of linear thermal expansion. The coefficient of linear thermal expansion generally varies with temperature.
- 9. Linear Expansion Linear expansion is the change in length due to heat. Linear expansion formula is given as, Δ���=��Δ� Where, L0 = original length, L = expanded length, α = length expansion coefficient, ΔT = temperature difference, ΔL = change in length Volume Expansion Volume expansion is the change in volume due to temperature. Volume expansion formula is given as Δ���=��Δ� Where, V0 = original volume, V = expanded volume, αv = volume expansion coefficient, ΔT = temperature difference, ΔV = change in volume after expansion Area Expansion Area expansion occurs is the change in area due to temperature change. Area expansion formula is given as, Δ���=��Δ� Where, A = original area, ΔA = change in the area, αA = area expansion coefficient, ΔT = temperature difference, A0 = expanded area.
- 10. What Is Energy? There are different forms of energy on earth. The sun is considered the elemental form of energy on earth. In physics, energy is considered a quantitative property that can be transferred from an object to perform work. Hence, we can define energy as the strength to do any kind of physical activity. Thus, in simple words, we can define energy as, Energy is the ability to do work According to the laws of conservation of energy, “ energy can neither be created nor destroyed but can only be converted from one form to another”. The SI unit of energy is Joule. Units of Energy The International System of Units of measurement of energy is joule. The unit of energy is named after James Prescott Joule. Joule is a derived unit equal to the energy expended in applying a force of one newton through a distance of one meter. However, energy is also expressed in manyother units not part of the SI, such as ergs, calories, British Thermal Units, kilowatt-hours, and kilocalories, which require a conversion factor when expressed in SI units. DifferentTypes of Energy Although there are many forms of energy, it is broadly categorized into: • Kinetic Energy • Potential Energy
- 11. Kinetic Energy Kinetic energy is the energy associated with the object’s motion. Objects in motion arecapable of causing a change or arecapable of doing work. To better understand, let us think of a wrecking ball. A wrecking ball in motion is used to do work such as the demolition of buildings, stones, etc. Even a slow-moving wrecking ball is capable of causing a lot of damage to another object, such as an empty house. However, a wrecking ball that is not in motion does not do any work. Another example of kinetic energy is the energy associated with the constant, randombouncing of atoms or molecules. This is also known as thermal energy. The averagethermal energy of a group of molecules is what we call temperature, and when thermal energy is transferred between two objects, it’s known as heat. DifferentTypes of Kinetic Energy: Radiant energy • Radiant energy is the type of energy that travels by waves or particles. This energy is created through electromagnetic wavesand is mostcommonly experienced by humans in the formof heat. Following area few examples of radiantenergy: • When you turn on an incandescent light bulb, it gives off two forms of energy. Thereis visible light and heat that is generated. Both these generated energies are a formof radiant energy. • Sunlight is an example of radiantenergy. Thermal Energy Thermal energy is similar to radiant energy and is experienced in the formof heat or warmth. While radiant energy refers to waves or particles, thermal energy describes the activity level among the atoms and molecules in an object. This is the only differencebetween radiantenergy and thermal energy. Someexamples of thermal energy include: • The geothermal energy that comes fromthe decay of naturalminerals and the volcanic action of the earth is an example of thermal energy. • When you heat up the pizza in the oven, you raisethe pizza’s temperature. Themolecules that make up the pizza movemore quickly when the pizza is piping hot. • The warmth you feel emanating fromthe engine is an example of thermal energy. Sound Energy Humans experience the vibrations that reach the human ear as sound. The disturbancemoves in the formof waves through a medium like air and reaches our eardrum. On reaching the eardrum, these vibrations areconverted into electrical signals and sent to the brain, which weinterpret as the sensation of sound. Electrical Energy The flow of negatively charged electrons around a circuitresults in electricity which we morecommonly refer to as electrical energy. Mechanical Energy Mechanical energy is the energy associated with the mechanical movement of objects. This type of energy can also be referred to as motion energy. Potential Energy Potential energy is the energy stored in an object or systemof objects. Potential energy can transforminto a moreobvious formof kinetic energy.
- 12. DifferentTypes Of Potential Energy Gravitational Potential Energy Gravitational potentialenergy is the energy stored in an object due to its vertical position or height. A book on a high bookshelf has a higher gravitational potentialenergy than a book on the bottom bookshelf. Gravitational Potential Energy Examples • River water at the top of a waterfall • A book on a table before it falls • A car that is parked at the top of a hill Elastic Potential Energy Elastic potentialenergy is stored as a result of applyinga force to deform an elastic object. The energy is stored untilthe force is removed and the object springs back to its originalshape, doing work in the process. The deformation could involve compressing, stretching or twisting the object. Elastic Potential Energy Examples • A spring that is coiled • The string of an archer’s bow is pulled back • Rubber band that has been stretched Chemical Potential Energy Chemical potentialenergy is the energy stored in the chemical bondsof the substance. The energy can be absorbed and released due to a change in the particle number of the given species. Chemical Potential Energy Examples • Before the sun shines on the green leaves (potential photosynthesis) • Gasoline before it is ignited • Fireworks before they are launched
- 13. ElectricPotential Energy Electric potentialenergy is the energy that is needed to move a charge againstan electric field. ElectricPotential Energy Examples • An incandescent light bulb that is turned off • A radio tower that is not working • A black-light turned off • A television before it is turned on Energy Conversion: Transfer and Transform We know energy can be transferred from one form to another. The movement of energy from one locationto another is known as energy transfer. We notice variousenergy transformations happeningaround us. Followingare the four ways through which energy can be transferred: • Mechanically – By the action of force • Electrically – Electrically • By Radiation – By Light waves or Sound waves • By Heating – By conduction, convection, or radiation The process which results in the energy changing from one form to another is known as energy transformation.While energy can be transformed or transferred, the total amount of energy does not change – this is called energy conservation. Law of Conservation of Energy The law of energy conservationis one of physics’s basic laws. It governs the microscopic motion of individual atomsin a chemical reaction. The law of conservationof energy states that “In a closed system, i.e., a system that is isolated from its surroundings, the total energy of the system is conserved.” According to the law, the totalenergy in a system is conserved even though energy transformation occurs. Energy can neither be created nor destroyed, it can only be converted from one form to another.