If heat flows from a cup of hot water to a bathtub full of cool water, the water in the cup will have a loss in ? 47. It was designed to give an engineering or technological flavour to the students’ physics course, within a wide range of contexts. How much more internal energy does this gas have than the same volume has at zero gauge pressure (which is equivalent to normal atmospheric pressure)? (Essentially: conservation of energy). Solution Do this by considering the number of ways that each could be formed (the number of microstates in each macrostate). In which of the paths between initial state i and final state f in the below figure is … Using Table, verify the contention that if you toss 100 coins each second, you can expect to get 100 heads or 100 tails once in \(\displaystyle 2×10^{22}\) calculate the time to two-digit accuracy. 64. Solution The temperature of the steam leaving the boiler is \(\displaystyle 550ºC \). Specific heat and latent heat of fusion and vaporization. These are practice examination questions on AC theory for A-Level Physics. Have questions or comments? … (d) What percent chance is there of tossing 5 heads and 1 tail? Thermodynamics to a system of thermodynamic components (heaters, coolers, pumps, turbines, pistons, etc.) chemical engineering? Does the entropy of the space into which it radiates (which has a temperature of about 3 K) increase or decrease? These are practice examination questions on kinetic theory of gases for A-Level Physics. The temperature of a body is increased from -173 C to 357 C. (a) Is the heat transfer converted directly to work in an isobaric process, or does it go through another form first? Construct a problem in which you calculate the overall efficiency of the car for the trip as a ratio of kinetic and potential energy gained to fuel consumed. In some Northern European nations, homes are being built without heating systems of any type. Solution (a) A cyclical heat engine, operating between temperatures of \(\displaystyle 450º C\) and \(\displaystyle 150º C\) produces 4.00 MJ of work on a heat transfer of 5.00 MJ into the engine. Solution Welcome to 5.1 THERMODYNAMICS. You could raise a car 12.5 kilometers with the energy in a gallon of gas. (d) Show that this is the same efficiency as a single Carnot engine operating between \(\displaystyle 450ºC\) and \(\displaystyle 150ºC\). The first law of thermodynamics and the conservation of energy, as discussed in Conservation of Energy, are clearly related. 58. Physics problems: thermodynamics. (b) What is unreasonable about the engine? 39. Calculate the net work output of a heat engine following path ABCDA in the figure below. ... at sea level (b) at the center of the earth (c) when molecular momentum of the system becomes zero (d) under vacuum conditions 99. Give Its Limitations And Importance.? 92. Suppose you want to operate an ideal refrigerator with a cold temperature of \(\displaystyle −10.0ºC\), and you would like it to have a coefficient of performance of 7.00. Explain your answer. The Carnot efficiency is \(\displaystyle Eff_C=1−\frac{T_c}{T_h}=1−\frac{300K}{600K}=0.50\). (c) Compare his work output with the daily output of a 187-W (0.250-horsepower) motor. ΔU=Q in −W Work done by the system Example: expanding gas pushes a piston Work done on the system Example: … (a) –56.3ºC How much heat transfer occurs to the environment? 87. In this article, students will get notes of chapter Thermodynamics including topics important concepts, formulae and previous years’ solved questions for WBJEE 2018. Does a gas become more orderly when it liquefies? (b) How much less heat transfer occurs to the environment by the more efficient power station? 1) QUES: A piece of brass undergoes 3 different processes involving change of energy: P : it is lifted vertically 2m Q : it is heated from 15 degrees Celsius to 20 degrees Celsius R : it is accelerated from … Resources About Services Blog Contact Resources About Services Blog (c) If ice costs 20 cents per kg, do you think the air conditioner could be operated more cheaply than by simply using ice? (c) If you were betting on 2 heads and 8 tails would you accept odds of 252 to 45? Driving up Pike's Peak (a mere 3000-meter climb) should consume a little less than a quart of gas. Appendix 6: Mathematical skills and exemplifications). This is the currently selected item. (a) What would the cold reservoir temperature be if this were a Carnot engine? 84. (b) Since \(\displaystyle 270ºC\) steam is still quite hot, a second steam engine is sometimes operated using the exhaust of the first. (a) Calculate the cold reservoir temperature of a steam engine that uses hot steam at \(\displaystyle 450ºC\) and has a Carnot efficiency of 0.700. (c) 64 This problem compares the energy output and heat transfer to the environment by two different types of nuclear power stations—one with the normal efficiency of 34.0%, and another with an improved efficiency of 40.0%. (c) Yes, since automobiles engines cannot get too hot without overheating, their efficiency is limited. As you know, we use a lot of energy to keep our houses warm in the winter because of the loss of heat to the outside. What is the change in entropy in an adiabatic process? In particular, which can be stored as such in a system and which cannot? Part 1 Problem 1. Steam locomotives have an efficiency of 17.0% and operate with a hot steam temperature of \(\displaystyle 425ºC\). Can you cool a kitchen by leaving the refrigerator door open? 23. The University does not release solutions to past exam questions, but numerical answers are: 2013 (b) Qout=500kJ, max … (a) Construct a table showing the macrostates and all of the individual microstates for tossing 6 coins. 36. The two cyclical processes shown on this \(\displaystyle PV\) diagram start with and return the system to the conditions at point A, but they follow different paths and produce different amounts of work. (A therm is a common unit of energy for natural gas and equals \(\displaystyle 1.055×10^8J\).). (e) How much more likely are you to toss 3 heads and 3 tails than 5 heads and 1 tail? A great deal of effort, time, and money has been spent in the quest for the so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces … How does the definition of efficiency in each relate to the type of energy being converted into doing work? What is the hot reservoir temperature for such a refrigerator? Assume that prior to the upgrade the power station had an efficiency of 36% and that the heat transfer into the engine in one day is still the same at \(\displaystyle 2.50×10^{14}J\). Explicitly show how you follow the steps in the Problem-Solving Strategies for Thermodynamics. (b) \(\displaystyle 54.1%\). But other considerations have to be taken into account. A system does \(\displaystyle 1.80×10^8J\) of work while \(\displaystyle 7.50×10^8J\) of heat transfer occurs to the environment. Does this assume no phase change takes place? 77. (Part of \(\displaystyle Q_c\) could be utilized to operate heat engines or for simply heating the surroundings, but it rarely is. Subscribe to A Level Physics to access 400+ resources, plus 15 new Factsheets each year. (b) What is the maximum amount of work in joules he can do without breaking down fat, assuming a maximum efficiency of 20.0%? (a) How much more electrical energy is produced due to the upgrade? Steam to drive an old-fashioned steam locomotive is supplied at a constant gauge pressure of \(\displaystyle 1.75×10^6N/m^2\) (about 250 psi) to a piston with a 0.200-m radius. tistical mechanics. Would you be willing to financially back an inventor who is marketing a device that she claims has 25 kJ of heat transfer at 600 K, has heat transfer to the environment at 300 K, and does 12 kJ of work? A car tire contains \(\displaystyle 0.0380m^3\) of air at a pressure of \(\displaystyle 2.20×10^5N/m^2\) (about 32 psi). Solution Consider a system with a certain energy content, from which we wish to extract as much work as possible. (a) In reaching equilibrium, how much heat transfer occurs from 1.00 kg of water at \(\displaystyle 40.0º C\) when it is placed in contact with 1.00 kg of \(\displaystyle 20.0º C\) water in reaching equilibrium? One method of converting heat transfer into doing work is for heat transfer into a gas to take place, which expands, doing work on a piston, as shown in the figure below. An ideal heat pump is being considered for use in heating an environment with a temperature of \(\displaystyle 22.0ºC\). Explain why a building made of bricks has smaller entropy than the same bricks in a disorganized pile. Question #122066. a)Suba (m=72.6 kg) is skiing from a hill. What does this do to the entropy of the universe? No one has entered the cottage in the meantime. (b) In order to gain more energy, we must generate it from things within the house, like a heat pump, human bodies, and other appliances. (a) \(\displaystyle 244ºC\) (b) How much less heat transfer occurs to the environment due to the upgrade? (b) 5.6 times more likely Consider that dissipative mechanisms are one cause of irreversibility. Ideal for students preparing for semester exams, GATE, IES, PSUs, NET/SET/JRF, UPSC and other entrance exams. Explain why or why not. A hot rock ejected from a volcano’s lava fountain cools from \(\displaystyle 1100º C\) to \(\displaystyle 40.0º C\), and its entropy decreases by 950 J/K. 27. \(\displaystyle ∴(1−Eff_{overall})=(1−Eff_1)(1−Eff_2)\) 15.2: The First Law of Thermodynamics and Some Simple Processes. 8. If you run down some stairs and stop, what happens to your kinetic energy and your initial gravitational potential energy? If the system as a whole is at rest, so that the bulk mechanical energy due to translational or rotational motion is zero, then the Solution The second law of thermodynamics. Imagine you are driving a car up Pike’s Peak in Colorado. Does its entropy change? (a) What is the hot reservoir temperature of a Carnot engine that has an efficiency of 42.0% and a cold reservoir temperature of \(\displaystyle 27.0ºC\)? The actual efficiency is 96% of the Carnot efficiency, which is much higher than the best-ever achieved of about 70%, so her scheme is likely to be fraudulent. How much heat transfer occurs from a system, if its internal energy decreased by 150 J while it was doing 30.0 J of work? (b) How many hours of operation would be equivalent to melting 900 kg of ice? 40. 28. What is the net work output of a heat engine that follows path ABDA in the figure above, with a straight line from B to D? With \(\displaystyle 2.56×10^6J\) of heat transfer into this engine, a given cyclical heat engine can do only \(\displaystyle 1.50×10^5J\) of work. 63. These are the answers to the thermodynamics practice questions for A-Level Physics. Assume that the turbines at a coal-powered power plant were upgraded, resulting in an improvement in efficiency of 3.32%. Even though thermodynamics may appear to be somewhat uninteresting to some of you, you should note that at the AP Physics B level you will often get unusually simple questions. The paper will include questions that target mathematics at Level 2 or above (see . 69. What is its coefficient of performance? 98. Why do refrigerators, air conditioners, and heat pumps operate most cost-effectively for cycles with a small difference between \(\displaystyle T_h\) and \(\displaystyle T_c\)? What would the hot reservoir temperature be for a Carnot engine having that efficiency, if it operates with a cold reservoir temperature of \(\displaystyle 200ºC\)? (a) How much heat transfer occurs to the environment? 52. (a) \(\displaystyle 3.80 × 10^9J\) (c) To transfer \(\displaystyle 1.66×10^8J\), heat pump costs $1.00, natural gas costs $1.34. We will now discus some typical multiple choice practice questions related to thermodynamics. Answer to Question #122066 in Molecular Physics | Thermodynamics for nini 2020-06-15T09:54:33-0400. (Take the ratio of the number of microstates to find out.). A rapidly spinning paddle wheel raises the temperature of 200mL of water from 21 degrees Celsius to 25 degrees. Where do we find more energy when such energy is lost to us? ), Solution NEET Physics - Mini Question Bank Thermodynamics questions & solutions with PDF and difficulty level (b) How much more likely is 5 heads and 5 tails than 2 heads and 8 tails? (b) \(\displaystyle 1.66×10^8J\) or \(\displaystyle 3.97×10^4kcal\) (b) \(\displaystyle –8.30 × 10^{12}J\), where the negative sign indicates a reduction in heat transfer to the environment. ), Solution (b) Find the ratio of this efficiency to the Carnot efficiency of a standard nuclear reactor (found in Example). (c) \(\displaystyle Eff_1=1−\frac{T_{c,1}}{T_{h,1}}⇒T_{c,1}=T_{h,1}(1,−,eff_1)\) similarly, \(\displaystyle T_{c,2}=T_{h,2}(1−Eff_2)\) Yes, the answer is the same. 68. 91. Solution These are the answers to the further kinetic theory of gases practice questions for A-Level Physics. When \(\displaystyle 1.60×10^5J\) of heat transfer occurs into a meat pie initially at \(\displaystyle 20.0º C\), its entropy increases by 480 J/K. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. A level Applied Physics Would knowledge of AS physics be helpful in chemistry? Note that the energy efficiency rating (\(\displaystyle EER\)) of an air conditioner or refrigerator is defined to be the number of British thermal units of heat transfer from a cold environment per hour divided by the watts of power input. What is the cold reservoir temperature if the pump is to have a coefficient of performance of 12.0? It is unlikely that a process can be isothermal unless it is a very slow process. (a) \(\displaystyle W=PΔV=1.76×10^5J\) (e) Discuss how everyday processes make increasingly more energy unavailable to do work, as implied by this problem. Explain why a building made of bricks has smaller entropy than the same bricks in a disorganized pile. 32. In which can heat transfer result in work done without heat transfer from another system? A level Physics revision. Calculate whether we can bring the relative humidity in the office up to the comfortable level by closing the air vents and putting a cup of … Thermodynamics Multiple choice Questions and answers pdf,mcqs,objective type questions,lab viva manual technical basic interview questions download. 97. How do they differ in the types of energy considered? (b) How much heat transfer occurs into the warm environment if \(\displaystyle 3.60×10^7J\) of work (10.0kW⋅h) is put into it? (b) What percent of the total possibilities is this? (Hint: Consider whether the gas does work and whether heat transfer occurs rapidly into the gas through conduction.). Hope u can help me :) I NEED WORKINGS PLZ! A great deal of effort, time, and money has been spent in the quest for the so-called perpetual-motion machine, which is defined as a hypothetical machine that operates or produces useful work indefinitely and/or a hypothetical machine that produces more work or energy than it consumes. What temperature of hot steam must you use? She is standing at 28.5 m from the earth surface level. Heat transfer \(\displaystyle Q\) and work done \(\displaystyle W\) are always energy in transit, whereas internal energy \(\displaystyle U\) is energy stored in a system. Can a process be precisely adiabatic for a macroscopic system? These are the answers to the thermodynamics practice questions for A-Level Physics. 62. A gas-cooled nuclear reactor operates between hot and cold reservoir temperatures of \(\displaystyle 700ºC\) and \(\displaystyle 27.0ºC\). 10. 71. All other factors, such as the car’s temperature, are constant. All the individuals who are currently preparing for any physics subject related exam or just want to improve their general knowledge related to this topic, should attempt these tests in order to complete … This work is licensed by OpenStax University Physics under a Creative Commons Attribution License (by 4.0). (c) What is the total number of microstates? Among the things to consider are the effective hot and cold reservoir temperatures. Here are a few important concepts that need to be covered while preparing for this chapter: The first law of thermodynamics. If her efficiency is 18.0%, how much heat transfer occurs to the environment to keep her temperature constant? (a) \(\displaystyle 8.30 × 10^{12}J\), which is 3.32% of \(\displaystyle 2.50 × 10^{14}J\). These are the answers to the work energy and power practice questions for A-Level Physics. (e) 3.33 times more likely (20 to 6). (Note that the temperatures of the cycle employed are crucial to its \(\displaystyle COP\).). Explain, in terms of heat engines and the first law of thermodynamics, why or why not such a machine is likely to be constructed. 81. (b) What is unreasonable about the temperature? Edexcel A Level Physics revision resources. 60. phd physics interview questions Thermodynamics basic definitions how hard is chemical engineering without physics a level? Structured or uniform? Compare this efficiency to the thermodynamic efficiency quoted for gasoline engines and discuss why the thermodynamic efficiency is so much greater. Give an example of each type of energy, and state specifically how it is either in transit or resides in a system. 49. (b) The temperature is too cold for the output of a steam engine (the local environment). Specifically, explain what happens to the entropy of its surroundings. At that rate, how long will it take on average to get either 10 heads and 0 tails or 0 heads and 10 tails? 94. (a) How long will the energy in a 1470-kJ (350-kcal) cup of yogurt last in a woman doing work at the rate of 150 W with an efficiency of 20.0% (such as in leisurely climbing stairs)? (b) \(\displaystyle 1.60×10^{14}J\) Explicitly show how you follow the steps in the Problem-Solving Strategies for Entropy. (a) What is the best coefficient of performance for a refrigerator that cools an environment at \(\displaystyle −30.0ºC\) and has heat transfer to another environment at \(\displaystyle 45.0ºC\)? Interview questions thermodynamics basic definitions how hard is chemical engineering without Physics a level { 30 } \.! They eliminate heat transfer occurs into the engine in one day on odds of 252 to 45 ) \ \displaystyle! Less heat transfer alone form first it is often seen as an different... 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Of contexts be able to successfully attempt Q2 on the piston, neglecting friction and force... Compare this efficiency to the environment to keep his temperature constant is \ ( 18.5kJ\. Hint: consider whether the gas through conduction. ). ). ). )..!
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