RESOLUÇÃO DE QUESTÕES DE CICLOS TERMODINÂMICOS | Professor Fabrício Pessoa

In this video, Professor Fabrício Pessoa is solving problems about thermodynamics. 00:00 | Start STATEMENTS OF THE SOLVED PROBLEMS: 00:37 | 1) (UNESP) To inflate a car tire at a service station, the recommendation is to put in about 30 PSI, an abbreviation in English for the pressure unit "pounds per square inch". For an airplane tire, which is filled with pure nitrogen instead of air, the recommended pressure is around 200 PSI at an ambient temperature of 300 K. However, during landing, this internal pressure can increase significantly as a consequence of the heat generated by the impact and friction with the ground and the action of the brakes, with the temperature potentially reaching 1200 K. (www.uol.com.br. Adapted.) Assuming the tire volume does not change, the internal nitrogen pressure in the tire during landing can reach a value of: a) 1000 PSI. b) 300 PSI. c) 600 PSI. d) 500 PSI. e) 800 PSI. 04:28 | 2) (Unicamp) One of the most difficult stages of a manned space flight is reentry into the Earth's atmosphere. Upon re-entering the upper atmosphere, the spacecraft undergoes significant deceleration, and its external temperature reaches thousands of degrees Celsius. If re-entry does not occur under appropriate conditions, there is a risk of serious damage to the spacecraft, including explosion, and even the risk of it being ejected back into space. Atmospheric air behaves like a perfect gas. Given that the pressure and temperature of the air at a certain position in the upper atmosphere are p = 2.0 Pa and T = 180 K (without the capsule in the vicinity), and given that the universal gas constant is R = 8 J/(mol.K), what is the volume occupied by one mole of air at that position? 07:05 | 3) (EEAR) A cylinder fitted with a piston contains 150 cm³ of an ideal gas trapped inside at a controlled temperature of 22 °C and a pressure of 2 Pa. Consider that the piston of the cylinder can be moved by an external force, so that the gas is compressed to one-third of its initial volume, without, however, varying its temperature. Under these conditions, determine in Pascal (Pa) the new pressure to which the gas will be subjected. 09:46 | 4) (UFRGS) In the following figure, the p x V diagrams represent two thermodynamic transformations of a sample of ideal gas. Transformations 1 and 2 are called, respectively, 12:09 | 5) (ENEM) A person opens their refrigerator, checks what is inside, and then closes the refrigerator door. Then, they try to open the refrigerator again, but can only do so after exerting a more intense force than usual. The extra difficulty in reopening the refrigerator occurs because the (a) 17:49 | 6) (UNICAMP) Ballooning, an aeronautical sport with followers worldwide, offers a beautiful spectacle for observers on the ground. A blowtorch is used to heat the air inside the balloon, which varies the air density, allowing control of the balloon's ascent and descent. A balloon has a volume V = 1.6 x 10³ m³ of hot air inside at a temperature T = 400 K and at atmospheric pressure O = 1.0 atm = 1.0 x 10⁵ Pa. Knowing that hot air behaves as an ideal gas and that the universal gas constant is R = 8 J/(mol.K), how many moles of air n are there inside the balloon? 21:04 | 7) (FER) An ideal gas undergoes an isobaric compression such that its volume is reduced to 2/3 of the initial volume. If the initial temperature of the gas was 150 °C, the final temperature, in °C, is: 23:32 | 8) (UFPR) The P x ​​V diagram on the side illustrates a sequence of thermodynamic processes performed by a monatomic ideal gas, passing through points A, B, C, and D, characterized by the pressure and volume values ​​presented in the diagram. Considering the information presented in the diagram, consider the following statements: 1. The process A → B is isometric. 2. Points C and D are at the same temperature. 3. The work done by the gas in the process B → C is zero. 4. The process C → D is isobaric. 27:12 | 9) (ENEM) Increasing the efficiency of fuel combustion in internal combustion engines and reducing their pollutant emissions are the goal of any engine manufacturer. It is also the focus of Brazilian research involving experiments with plasma, the fourth state of matter, which is present in the ignition process. The interaction of the spark emitted by the spark plug with the fuel molecules generates the plasma that causes the energy-releasing explosion that, in turn, makes the engine work. However, the pursuit of efficiency referenced in the text presents a limiting factor: 31:15 | 10) (UDESC) A steam engine was designed to operate between two heat sources, a hot source and a cold source, and to work according to the Carnot cycle. It is known that the temperature of the hot source is 127 °C and that the engine extracts 600 J from this source in each cycle, achieving a maximum efficiency of 0.25. The work done by the engine per cycle and the temperature of the cold source are, respectively: