Concept explainers
Note: In the following problems, you will deal with both the International System of Units (SI) (N, kg, m, s, K) and the English Engineering System (lb, slug, ft, s,
Calculate the percentage error obtained if Problem 7.9 is solved using (incorrectly) the incompressible Bernoulli equation.
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Fundamentals of Aerodynamics
- The correct statement in relation to first law of thermodynamics i.e. Q=W+AU is, .. [A] Q is negative if heat is absorbed by the system and Q is positive if heat is released by the system [B] AU is negative if internal energy of the system increases and AU is positive if internal energy of the system decreases [C] W is positive if work is done on the system and W is negative if work is done by the system [D] Q is a path function, W is a path function and A U is a state functionarrow_forwardA vertical piston-cylinder arrangement with a diameter of 120 mm contains water with a quality of 60%. The pressure is 3 bar. Initially the piston rests 40 mm above the bottom of the cylinder. Heat is then added until the volume is 3 times the original volume. (a) Determine the mass of the water in the cylinder [ Select ] O kg (b) Determine the work done. [ Select ] O (J) (c) The final temperature [ Select ] O °C (d) The heat transferred to the system [ Select ]arrow_forwardThe gravitational constant g is 9.807 m/s2 at sea level, but it decreases as you go up in elevation. A useful equation for this decrease in g is g = a – bz, where z is the elevation above sea level, a = 9.807 m/s2, and b = 3.32 × 10–6 1/s2. An astronaut “weighs” 80.0 kg at sea level. [Technically this means that his/her mass is 80.0 kg.] Calculate this person’s weight in N while floating around in the International Space Station (z = 354 km). If the Space Station were to suddenly stop in its orbit, what gravitational acceleration would the astronaut feel immediately after the satellite stopped moving? In light of your answer, explain why astronauts on the Space Station feel “weightless.”arrow_forward
- A commonly used unit in everyday language to state weight is the pound (lb). There are actually several formal definitions of pound. One classification system defines a pound-mass (analogous to kg in SI units) and a pound-force (lbf) (analogous to a Newton); this is formally called English Engineering units but also commonly used in US Customary System units. The “pound” in the “pounds per square inch” of psi refers to pound-force. Hence, psi has units of force per area. Note that 1 lbf is defined as the gravitational force generated by 1 lb (mass) by multiplying it by the standard gravitational acceleration at the earth’s surface. Starting with just the two everyday conversion approximations every Canadian should know (1.00 kg ≈ 2.20 lb (mass) and 1.00 inch ≈ 2.54 cm), derive an approximation of 1.00 psi in Pa through unit conversions only (show each step).arrow_forward74 PROBLEMS : A cube of wood floats in oil with a relative density of 0,78 so that half of the cube is out of the oil. The mass of the cube is 2 kg. (a) Determine the dimensions of the cube. [0,172 m] (b) To what depth will a 3 kg cube of the same wood sink in sea water with a density of 1 025 kg/m³ . [0,075 m] (c) Determine the mass to be added to a 6 kg block of the" same wood so that the block will sink in sea water. [9,765- kg]arrow_forwardIn medical literatures, local blood perfusion rate is typically presented as xx ml/(min 100g tissue), in another word, it represents xx ml of blood supplied to a tissue mass of 100 g per minute to satisfy its nutritional needs. As we learned from the course lectures, the local blood perfusion rate appearing in the Pennes bioheat equation is in a unit of 1/s, or can be interpreted as xx ml of blood supplied to a tissue volume of 1 ml per second. The following lists the blood perfusion rates in various organs or structures in a human body from medical textbooks: brain (50 ml/(min 100g tissue)), kidney (35 ml/(min 100g tissue)), and muscle at rest (3 ml/(min 100g tissue)). Please convert the above local blood perfusion rates into values with the unit of 1/s, therefore, they can be used in the Pennes bioheat equation. The tissue density in a human body is 1050 kg/m³.arrow_forward
- 1. Find the force required to move a load of 300 N up a rough plane, the force being applied parallel to the plane. The inclination of the plane is such that a force of 60 N inclined at 30° to a similar smooth plane would keep the same load in equilibrium. The coefficient of friction is 0.3. [Ans. 146 N]arrow_forward2. Complete the blank cells in the following table of properties of steam. In the last column describe the condition of steam as compressed liquid, saturated mixture, superheated vapor, or insufficient information; and, if applicable, give the quality. P[kPa] T[°C] v[m³/kg] а. 500 20 b. 500 0.20 с. 1400 200 d. 300 0.8arrow_forwardA hemispherical container, 26 inches in diameter, is filled with a liquid at 20°C and weighed. The liquid weight is found to be 1617 ounces. What is the density of the fluid in kg/m3? ]kg/m3arrow_forward
- Complete the following table for saturated water. Temp T ("C) Pressure P Entropy s (kJ/kg.K) Quality x Phase description (kPa) 120 5000 [1.1]? [1.2]? [1.3]? 50 1000 [1.4]? [1.5]? [1.6]? 400 1800 [1.7]? [1.8]? [1.9]? [1.10]? 40 [1.11]? X = 0.9 [1.12]?arrow_forwardThere are different types of pressures: atmospheric, barometric, gauge, absolute and vacuum pressure. Refer to Figure 5.18 below: Vacuum Vacuum Helium 20inHg Helium 30inHg , 宁大 (a) (b) (c) (a) What kind of pressure (the 20 inHg) is measured in Figure 5.18 (a)? (b) What kind of pressure (the 30 inHg) is measured in Figure 5.18 (b)? (c) What would the h reading Figure 5.18 (c) assuming that the pressure and temperature inside and outside the helium tank are the same as in part (a) and (b)?arrow_forward36. In a car tire are 9.0 dm³ air at 12 °C under a inflation pressure of 2.2 bar. During a long journey, the air inside the tire warms up to 76 °C as a result of flexing and sunlight. The tire extends insofar that the new air volume is 9.4 dm. Which inflation pressure prevails in the tire? [pressure 2.75 bar]arrow_forward
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