Which of the following variables controls the physical properties of a perfect gas a pressure b temperature c volume d all of the above e atomic mass. Ans: d. The unit of temperature in S. The unit of mass in S. Ans: a. The unit of time in S. The unit of length in S. The unit of energy in S. Ans: b. According to Gay-Lussac law for a perfect gas, the absolute pressure of given mass varies directly as a temperature b absolute c absolute temperature, if volume is kept constant d volume, if temperature is kept constant e remains constant,if volume and temperature are kept constant.
Ans: c. An ideal gas as compared to a real gas at very high pressure occupies a more volume b less volume c same volume d unpredictable behaviour e no such correlation. Which of the following can be regarded as gas so that gas laws could be applicable, within the commonly encountered temperature limits. The unit of pressure in S. A closed system is one in which a mass does not cross boundaries of the system, though energy may do so b mass crosses the boundary but not the energy c neither mass nor energy crosses the boundaries of the system d both energy and mass cross the boundaries of the system e thermodynamic reactions take place.
Temperature of a gas is produced due to a its heating value b kinetic energy of molecules c repulsion of molecules d attraction of molecules e surface tension of molecules. According to kinetic theory of gases, the absolute zero temperature is attained when a volume of the gas is zero b pressure of the gas is zero c kinetic energy of the molecules is zero d specific heat of gas is zero e mass is zero.
300+ TOP HEAT TRANSFER Multiple Choice Questions and Answers
Kinetic theory of gases assumes that the collisions between the molecules are a perfectly elastic b perfectly inelastic c partly elastic d partly inelastic e partly elastic and partly inelastic. Superheated vapour behaves a exactly as gas b as steam c as ordinary vapour d approximately as a gas e as average of gas and vapour.
The unit of power in S. The condition of perfect vacuum, i. Intensive property of a system is one whose value a depends on the mass of the system, like volume b does not depend on the mass of the system, like temperature, pressure, etc. Specific heat of air at constant pressure is equal to a 0. The behaviour of gases can be fully determined by a 1 law b 2 laws c 3 laws d 4 laws Ans: d.
The ratio of two specific heats of air is equal to a 0. The same volume of all gases would represent their a densities b specific weights c molecular weights d gas characteristic constants e specific gravities. An open system is one in which a mass does not cross boundaries of the system, though energy may do so b neither mass nor energy crosses the boundaries of the system c both energy and mass cross the boundaries of the system d mass crosses the boundary but not the energy e thermodynamic reactions do not occur.
Ans: e. Gases have a only one value of specific heat b two values of specific heat c three values of specific heat d no value of specific heat e under some conditions one value and sometimes two values of specific heat. Extensive property of a system is one whose value a depends on the mass of the system like volume b does not depend on the mass of the system, like temperature, pressure, etc.
To convert volumetric analysis to gravimetric analysis, the relative volume of each constituent of the flue gases is a divided by its molecular weight b multiplied by its molecular weight c multiplied by its density d multiplied by its specific weight e divided by its specific weight.
An isolated system is one in which a mass does not cross boundaries of the system, though energy may do so b neither mass nor energy crosses the boundaries of the system c both energy and mass cross the boundaries of the system d mass crosses the boundary but not the energy e thermodynamic reactions do not occur.
Properties of substances like pressure, temperature and density, in thermodynamic coordinates are a path functions b point functions c cyclic functions d real functions e thermodynamic functions. Which of the following quantities is not the property of the system a pressure b temperature c specific volume d heat e density.Most curricular materials in TeachEngineering are hierarchically organized; i.
Some activities or lessons, however, were developed to stand alone, and hence, they might not conform to this strict hierarchy. Related Curriculum shows how the document you are currently viewing fits into this hierarchy of curricular materials. A burning match is an example of heat transfer. All rights reserved. It is particularly relevant for civil, mechanical and chemical engineers because heat transfer plays a key role in material selection, machinery efficiency and reaction kinetics, respectively.
In this lesson, students learn how heat transfer applies to engineering and are asked to consider examples of engineering designs that have capitalized on the scientific principles of heat transfer.
Each TeachEngineering lesson or activity is correlated to one or more K science, technology, engineering or math STEM educational standards. In the ASN, standards are hierarchically structured: first by source; e. Plan and conduct an investigation to provide evidence that the transfer of thermal energy when two components of different temperature are combined within a closed system results in a more uniform energy distribution among the components in the system second law of thermodynamics.
Grades 9 - Do you agree with this alignment? Thanks for your feedback! Alignment agreement: Thanks for your feedback! Develop and use models to illustrate that energy at the macroscopic scale can be accounted for as either motions of particles or energy stored in fields.
View aligned curriculum. Students should be familiar with the concept of energy and the law of conservation of energy. They should also have a basic knowledge of high school chemistry. In advance, make copies of the Heat Transfer Guided Notes Worksheetone per student, and have handy a few ice cubes for a quick demo. Hand out the worksheets now, to help students stay engaged and follow the content as it is presented. The guided notes focus on definitions and heat transfer examples.
Today we are going to talk about a concept that will sound familiar to you: heat. Although I am sure that you have heard the word heat before, today we are going to discuss the science and physics behind what heat really is. Can anyone describe a situation in which you remember feeling the most cold or most hot that you have ever felt?
Listen to a few students. Avoid storytelling and sidetracking conversations. Have any of you burned yourself while cooking, or maybe experienced frostbite while in the snow? Listen to a few student examples. When we talk about being hot or cold, we are discussing temperature. Temperature is the measure of the average thermal energy in a system.
Write the definition on the classroom board. If an object, such as a baking pan, has a lot of energy, then it feels hot, but if it has less energy, then it feels less hot. Possible answers: Metal, molecules, atoms.
If you recall from your chemistry class, a baking pan is made of billions and billions of atoms that all vibrate and move in place. As we learned in our unit about energy, anything that is moving has kinetic energy, which is why we define temperature as the measure of the energy in a system.Unit of thermal conductivity in M.
Ans: b. Unit of thermal conductivity in S. Ans: e. Thermal conductivity of solid metals with rise in temperature normally a increases b decreases c remains constant d may increase or decrease depending on temperature e unpredictable. Thermal conductivity of non-metallic amorphous solids with decrease in temperature a increases b decreases c remains constant d may increase or decrease depending on temperature e unpredictable.
Ans: c. When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by a conduction b convection c radiation d conduction and convection e convection and radiation. Ans: a. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by a conduction b convection c radiation d conduction and convection e convection and radiation.
Sensible heat is the heat required to a change vapour into liquid b change liquid into vapour c increase the temperature of a liquid of vapour d convert water into steam and superheat it e convert saturated steam into dry steam.
When heat is Transferred by molecular collision, it is referred to as heat transfer by a conduction b convection c radiation d scattering e convection and radiation. Heat transfer in liquid and gases takes place by a conduction b convection c radiation d conduction and convection e convection and radiation. Which of the following is the case of heat transfer by radiation a blast furnace b heating of building c cooling of parts in furnace d heat received by a person from fireplace e all of the above.
Ans: d. Heat is closely related with a liquids b energy c temperature d entropy e enthalpy. Pick up the wrong case. Heat flowing from one side to other depends directly on a face area b time c thickness d temperature difference e thermal conductivity. Metals are good conductors of heat because a their atoms collide frequently b their atoms-are relatively far apart c they contain free electrons d they have high density e all of the above.
Which of the following is a case of steady state heat transfer a I. Total heat is the heat required to a change vapour into liquid b change liquid into vapour c increase the temperature of a liquid or vapour d convert water into steam and superheat it e convert saturated steam into dry steam.
Cork is a good insulator because it has a free electrons b atoms colliding frequency c low density d porous body e all of the above. Thermal conductivity of water in general with rise in temperature a increases b decreases c remains constant d may increase or decrease depending on temperature e none of the above.
Thermal conductivity of air with rise in temperature a increases b decreases c remains constant d may increase or decrease depending on temperature e none of the above. Heat flows from one body to other when they have a different heat contents b different specific heat c different atomic structure d different temperatures e none of the above. The amount of heat flow through a body by conduction is a directly proportional to the surface area of the body b directly proportional to the temperature difference on the two faces of the body c dependent upon the material of the body d inversely proportional to the thickness of the body e all of the above.
Which of the following has least value of conductivity a glass b water c plastic d rubber e air. Which of the following is expected to have highest thermal conductivity a steam b solid ice c melting ice d water e boiling water.
Thermal conductivity of glass-wool varies from sample to sample because of variation in a composition b density c porosity d structure e all of the above. Which of the following has maximum value of thermal conductivity a aluminium b steel c brass d copper e lead. Moisture would find its way into insulation by vapour pressure unless it is prevented by a high thickness of insulation b high vapour pressure c less thermal conductivity insulator d a vapour seal e all of the above.
Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in a electric heater b steam condenser c melting of ice d refrigerator condenser coils e boiler.Click on the image to see an enhanced diagram. By Nasif Nahle. Heat is energy in transit from warmer systems to colder systems.
Heat is associated with the internal potential and kinetic energy an apparently disorganized molecular motion of a system. The answer is: heat could be transferred from warmed systems by radiation. The thermal radiation is electromagnetic radiation that consists of particles and waves, i. Thus, the radiative heat transfer can take place through vacuum. The energy always moves from a warmer system to a colder system.
The energy which is moving from one system to another is known as heat. The transfer or dispersion of heat can occur by means of three main mechanisms, conduction, convection and radiation:. The molecules of a given point of a system which are at higher temperature vibrate faster than the molecules of other points of the same system -or of other systems- which are at lower temperature. The molecules with a higher movement collide with the less energized molecules and transfer part of their energy to the less energized molecules of the colder regions of the structure.
For example, the heat transfer by conduction through the bodywork of a car. Metals are the best thermal conductors; while non-metals are poor thermal conductors. The thermal conductivity of the carbon dioxide CO2 is 0. Formula to calculate the conductivity gradient for a given system:. Convection is the displacement of volumes of a substance in a liquid or gaseous phase. When a mass of a fluid is heated up, for example when it is in contact with a warmer surface, its molecules are carried away and scattered causing that the mass of that fluid becomes less dense.
Through this process, the molecules of the hot fluid transfer heat continuously toward the volumes of the colder fluid. For example, when heating up water on a stove, the volume of water at the bottom of the pot will be warmed up by conduction from the metallic bottom of the pot and its density decreases.
Given that it gets lesser dense, it shifts upwards up to the surface of the volume of water and displaces the upper -colder and denser- mass of water downwards, to the bottom of the pot. Formula of Convection:. It does not need a propagating medium. The energy transferred by radiation moves at the speed of light. The heat radiated by the Sun can be exchanged between the solar surface and the Earth's surface without heating the transitional space.
For example, if I place an object such as a coin, a car, or myself under the direct sunbeams, I will note in a little while that the object will be heated.June, Source: NASA. Solar power drives Earth's climate.
Energy from the sun heats Earth's surface, warms the atmosphere, provides energy for photosynthesis, causes evaporation, drives the weather and water cycles, and powers the ocean currents. In the astronaut photograph at right, taken from the International Space Station, you can see the sun setting through the atmosphere. When we look up at the sky from the ground, the atmosphere seems to go on forever, but in reality it is extremely thin when compared to the diameter of Earth.
To get a sense of the thickness of the troposphere and stratosphere, two important layers of the atmosphere, try this simple exercise. Use a compass to draw a circle with a radius of mm. This circle represents the Earth and the inner-most atmosphere. The 1 mm line, that your pencil draws, represents the average thickness of the the first two layers of the atmosphere: the troposphere, the region of weather, and the stratosphere, which protects us from most of the Sun's harmful ultraviolet UV radiation.
As you work through the these labs keep this relative scale in mind. Show me more about this example Hide In the example below, the line represents the thickness of the atmosphere to the top of the stratosphere 50 km above the surface.
Ninety-nine percent of the mass of the atmosphere's gases are within 32 km of Earth's surface, in these two layers.
The troposphere alone contains percent of the mass of the atmosphere. In the picture below, pixels are used as a measure of distance. To get a feel for how "thin" the atmosphere is, you might want to try this activity outdoors, using a scale of meters. Radiation is the transfer of energy by electromagnetic waves, which are invisible. You have probably seen a heat lamp warming food in a cafeteria; the heat lamp is using one type of long-wave electromagnetic radiation, infrared infrared radiation: the long wave, electromagnetic radiation of radiant heat emitted by all hot objects.
On the electromagnetic spectrum, it can be found between microwave radiation and visible light. Energy is transferred from the sun to Earth via electromagnetic waves, or radiation. Most of the energy that passes through the upper atmosphere and reaches Earth's surface is in two forms, visible and infrared light. The majority of this light is in the visible spectrum.
As sunlight enters the Earth system one of two different things can happen: it can either be absorbed or reflected. Once energy has been absorbed by the Earth system, it is transformed and transferred.
Eventually, after multiple transfers, this radiation is emitted back to space, keeping our planet in an energy equilibrium.The five categories included in the peer review process are.
In this activity students investigate how hurricanes transfer heat by conducting hands-on experiments. In this lab students work in groups to conduct simple laboratory experiments. It was designed for high school Earth Science students but is also applicable to introductory level students in college Geoscience courses. One minute class period is required for the activity.
There are six stations that the groups will rotate between so, depending on your class length, each station should take between 8 and 10 minutes. The lab requires common lab equipment like Bunsen burners and having it set up in a space designed for laboratory work is recommended. One piece of uncommon equipment is also called for in the form of an infrared thermometer for Station 1.
More information about this item can be found in the Teaching Notes and Tips section below. This lab requires a fair amount of pre-class setup. You will need to put together the different exercises at different stations.
Climate and Earth's Energy Balance
There are 6 stations in the lab so you will need to divide your class into 6 teams. Ideally of students each, but class size may not allow it. The teams will move from station to station, completing the exercises cooperatively as they go. This file is only accessible to verified educators. If you would like access to this file, please enter your email address below.
Heat Transfer - Radiation, Convection And Conduction
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Email Adress Submit. Cooperative Learning. The instructor will need to be moving around the room troubleshooting issues with equipment, although most of the materials in this lab are very simple.
The instructor should also be aware of how the groups are working together. Have a new can of compressed gas for each group so that everyone starts with a can at room temperature. Be sure students are pointing the laser dot at the center of the can while taking measurements. This will give them the best measurement accuracy. The day before conducting the lab, fill the beakers with water and put a small amount of pencil shavings or parsley flakes on top.
Over night they should settle to the bottom of the beaker. Have a separate beaker for each group so that they all get to see the convection start from scratch. The larger sized beakers make the convection easier to see. Only add a small amount of particles to the water. A large amount of shavings will cause clumping on the bottom of the beaker and reduce the visibility of the circulation.
Be sure to talk to the students about safety regarding the burners and that they wear the hand and eye protection during the activity.
Be sure to find out what the elevation is at your location so that you can give the students the proper chart to use on this activity. The piece of cardboard should be sized to accommodate the thermometers you have available with room for the students to label both.
Regular tennis shoe laces are hollow which will enable them to be slipped directly over the bulb of the wet thermometer. Make sure that students do it this way and don't just wrap the lace around bulb. Estimating the area of cooling in the image may give some students pause. They may have difficulty with converting to km using the scale bar or figuring out how to come up with an estimated area.
In the first case, have them measure the scale bar with their ruler so that they can convert any measurements from the image directly into km before making calculations. In the second case, you might share with them that the cooled area resembles a right triangle and they could make an estimate using that knowledge.Heat rises through convection, then transfters through the roof materials through conduction. The less dense atoms would become more buoyant than the cooler, denser atoms around them and would rise.
It is helpful for students to access their prior knowledge by having a discussion about how different surfaces absorb different amounts of energy from the Sun. This can include temperature differences in beach parking lots, the sand, and water. Teachers can also discuss with students how different colors of clothing absorb different amounts of radiation. Prior to conducting this activity, it may be helpful to take your class outside to the school parking lot.
Have them touch the dark pavement with their hands and note how hot it feels. Have students then touch white paint used for marking parking spots. Discuss why each surface has a different temperature. Note: Pavements can get really hot! Have students be careful as they touch the pavement. Then, conduct the activity. Model how to set up the thermometers in each of the bottles. Be sure students do not insert the thermometers into the bottles too far, preventing them from properly recording temperature.
Show the students how to attach the black and white paper to the soda bottles. Discuss with the students the importance of making sure the light source is the same distance from each of the bottles. Discuss with students what errors would occur if the bottles were not placed equal distances from the light source. Data will vary. The black bottle should become warmer at a faster rate than the white bottle. Student products will vary. Some possible research topics include: thermal vents, arctic regions, deserts Death Valleymountain tops Everest, etc.