Copy of 1.3.3.A Thermodynamics-PJP

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Apr 3, 2024

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Activity 1.3.3 Thermodynamics Introduction Think back to the last time someone complained about a door being left open. What did you notice about the temperature within the room as a result of the open door? In Activity 1.3.3 you will investigate the effects of work, thermal energy, and energy on a system, as in the case of the room with the door left open. Procedure Answer the following questions as your teacher discusses the Introduction to Thermodynamics presentation. Define thermodynamics. The study of the effects of work, heat flow, and energy on a system List three examples of a thermodynamic system. Washing machines, refrigerators and air-conditioners. Define thermal energy. kinetic energy in transit from one object to another due to temperature difference. Define temperature. The average kinetic energy of particles in an object Fill in the table below with the correct scale and unit. Scale Freezing point of water Boiling point of water Celsius 0°C 100°C © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 1

Fahrenheit 32°F 212°F Kelvin 273K 373K Define absolute zero. When all kinetic energy is removed from a object Define thermal equilibrium. The state obtained when touching objects within a system reach the same temperature. Define the Zeroth Law of Thermodynamics. If two systems are separately found to be in thermal equilibrium with a third system, the first two systems are in thermal equilibrium with each other. Define the 1st Law of Thermodynamics. Thermal energy can change form and location, but it cannot be created or destroyed, and Thermal energy can be increased within a system by adding thermal energy or by performing work in a system. List two ways thermal energy can be increased in a system. Add heat or pressure Define the 2nd Law of Thermodynamics. Thermal energy flows from hot to cold Define entropy. The measure of how evenly distributed heat is within a system. Define convection. The transfer of thermal energy by movement of fluid (liquid or gas) © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 2

List two examples of convection. Boiler heating systems, hot air balloon Define conduction. The transfer of thermal energy within an object or between objects from molecule to molecule List two examples of conduction. Feet burning on sand, Pot of water being heated up by stove © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 3

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Conduction Equations: ? = 𝑚 𝑐 ∆𝑇 ? = 𝑘𝐴∆𝑇/ 𝐿 𝑘 = ?𝐿/𝐴∆𝑇 ? = ?/∆𝑇 Define the following variables. Q = Energy transfer (joules) m = mass of the material (kilograms) c = specific heat capacity of the material (J/kg/*C P = rate of energy transfer (Watts) Δt = Change in time (seconds) k = thermal conductivity A = Area of thermal conductivity L = thickness of material ΔT = difference in temperature Define U-value. The measure of a materials ability to conduct heat Define R-value. Thermal resistance of a material © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 4

Define radiation. The process by which energy is transmitted through a medium, including empty space, as electromagnetic waves List two examples of radiation. X-rays, heat from the sun Define Stefan’s Law. All objects lose and gain thermal energy by electromagnetic radiation © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 5

A 1.00kg piece of aluminum metal at 90.0°C is placed in 4.00 liters (=4.00 kg) of water at 25.0°C. Determine the final temperature (T f ). List all known values. Mass (m) = 1.00kg Specific heat capacity of water (cw) = 4184 j/kgx*C Change in temperature (^t) unknown Change in thermal energy = 65.0*C List all unknown values. Select equations. M * C * ^T - mh20 * Ch20 ^ Th20 Apply known values. Solve. © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 6

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A 3/16 in. thick acrylic testing box with dimensions of 10.0 in. x 10.0 in. is covered with an unknown 0.50 in. insulation material. Determine the thermal conductivity for the insulating material if a 25.0W bulb is used to heat the box. The bulb maintains the inside temperature at 10.0ºC higher than the outside temperature. List all known values. List all unknown values. Select equations. Apply known values. Solve. © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 7

Use the provided R-value chart and the illustration below to calculate the R-value of the wall cavity and the R-value at the stud location. Wall cavity R-value R-value at stud location © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 8

R-Value Chart Construction Material R-Value ½ in. Drywall 0.45 5/8 in. Drywall 0.56 Particle Board – ½ in. 0.63 Particle Board – ¾ in. 0.94 Fiberboard ½ in. 1.32 Extruded Polystyrene 1 in. 4.00 Extruded Polystyrene 1 ½ in. 6.00 Foil-faced Polyisocyanurate 1 in. 7.20 2 x 4 4.38 2 x 6 6.88 Hardwood 0.90 Masonry Systems R-Value Brick 4 in. common 0.80 Brick 4 in. face 0.44 Concrete Block – Normal wt. 12 in. empty core 1.23 Concrete Block – Light wt. 12 in. empty core 2.60 - 2.30 Cement Mortar 0.20 Sand and Gravel 0.60 Stucco 0.20 Roofing R-Value Asphalt Roll 0.15 Asphalt Shingle 0.44 Slate 0.05 Wood 0.94 Siding R-Value Wood Shingles 0.87 Wood Drop 0.79 Wood Bevel Lapped 0.80 Aluminum/Steel – Hollow 0.61 Aluminum/Steel – with 3/8 in. Backer 1.82 Insulation R-Value per in. Fiberglass Batt 3.142 Blankets – Rock Wool 3.0 - 3.8 Loose Fill – Cellulose 2.8 - 3.7 Loose Fill – Fiberglass 0.7 lb/cu.ft 2.2 - 4.0 Loose Fill – Rock Wool 3.1 Loose Fill – Vermiculite 2.2 Extruded Polystyrene 4.00 © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 9

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A student travels on a school bus in the middle of winter from home to school. The school bus temperature is 58.0° F. The student’s skin temperature is 91.4° F. Determine the net energy transfer from the student’s body during the 20.00 min ride to school due to electromagnetic radiation. Note: Skin emissivity is 0.90, and the surface area of the student is 1.50m 2 . List all known values. List all unknown values. Select equations. Apply known values to equations. Solve. © 2012 Project Lead The Way, Inc. Principles Of Engineering Activity 1.3.3 Thermodynamics – Page 10