Concept explainers
You are watching a new bridge being built near your house. You notice during the construction that two concrete spans are placed end to end to form a span of length Li. However, they are placed end to end so that no room is allowed for expansion (Fig. P18.11a). In the opening storyline for this chapter, we talked about buckling sidewalks. The same thing will happen with spans on bridges if allowance is not made for expansion (Fig. P18.11b). You want to warn the construction crew about this dangerous situation, so you calculate the height y to which the spans will rise when they buckle in response to a temperature increase of ΔT.
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Chapter 19 Solutions
Physics for Scientists and Engineers, Technology Update (No access codes included)
- A vertical cylinder of cross-sectional area A is fitted with a tight-fitting, frictionless piston of mass m (Fig. P18.40). The piston is not restricted in its motion in any way and is supported by the gas at pressure P below it. Atmospheric pressure is P0. We wish to find the height h in Figure P18.40. (a) What analysis model is appropriate to describe the piston? (b) Write an appropriate force equation for the piston from this analysis model in terms of P, P0, m, A, and g. (c) Suppose n moles of an ideal gas are in the cylinder at a temperature of T. Substitute for P in your answer to part (b) to find the height h of the piston above the bottom of the cylinder. Figure P18.40arrow_forwardA vertical cylinder of cross-sectional area A is fitted with a tight-fitting, frictionless piston of mass m (Fig. P16.56). The piston is not restricted in its motion in any way and is supported by the gas at pressure P below it. Atmospheric pressure is P0. We wish to find die height h in Figure P16.56. (a) What analysis model is appropriate to describe the piston? (b) Write an appropriate force equation for the piston from this analysis model in terms of P, P0, m, A, and g. (c) Suppose n moles of an ideal gas are in the cylinder at a temperature of T. Substitute for P in your answer to part (b) to find the height h of the piston above the bottom of the cylinder.arrow_forwardDuring inhalation, a person's diaphragm and intercostal muscles contract, expanding the chest cavity and lowering the internal air pressure below ambient so that air flows in through the mouth and nose to the lungs. Suppose a person's lungs hold 1240 mL of air at a pressure of 1.00 atm. If they expand their chest cavity by 515 mL while keeping their nose and mouth closed so that no air is inhaled, what will be the air pressure in their lungs in atm? Assume the air temperature remains constant.arrow_forward
- During inhalation, a person's diaphragm and intercostal muscles contract, expanding the chest cavity and lowering the internal air pressure below ambient so that air flows in through the mouth and nose to the lungs. Suppose a person's lungs hold 1260 mL of air at a pressure of 1.00 atm. If they expand their chest cavity by 485 mL while keeping their nose and mouth closed so that no air is inhaled, what will be the air pressure in their lungs in atm? Assume the air temperature remains constant. HINT atmarrow_forwardDuring inhalation, a person's diaphragm and intercostal muscles contract, expanding the chest cavity and lowering the internal air pressure below ambient so that air flows in through the mouth and nose to the lungs. Suppose a person's lungs hold 1220 mL of air at a pressure of 1.00 atm. If they expand their chest cavity by 530 mL while keeping their nose and mouth closed so that no air is inhaled, what will be the air pressure in their lungs in atm? Assume the air temperature remains constant. HINT atm Need Help? Read It Watch Itarrow_forward(a) Determine the work done on a fluid that expands from i to f as indicated in Figure P12.10. (b) How much work is done on the fluid if it is compressed from f to i along the same path?arrow_forward
- During inhalation, a person's diaphragm and intercostal muscles contract, expanding the chest cavity and lowering the internal air pressure below ambient so that air flows in through the mouth and nose to the lungs. Suppose a person's lungs hold 1220 mL of air at a pressure of 1.00 atm. If they expand their chest cavity by 485 mL while keeping their nose and mouth closed so that no air is inhaled, what will be the air pressure in their lungs in atm? Assume the air temperature remains constant. atmarrow_forwardBy how much does a 20 m steel girder on a bridge expand or shrink from an average -7o C winter to an average 36o C summer? Express you answer in units of millimeters (mm), where 1000 mm = 1 m. expand by 6.96 mm expand by 10.32 mm shrink by 6.96 mm shrink by 0.1 mmarrow_forwardA 40.0-g projectile is launched by the expansion of hot gas in an arrangement shown in Figure P12.4a. The cross-sectional area of the launch tube is 1.0 cm2, and the length that the projectile travels down the tube after starting from rest is 32 cm. As the gas expands, the pressure varies as shown in Figure P12.4b. The values for the initial pressure and volume are Pi = 11 x 105 Pa and Vi = 8.0 cm3 while the final values arePf = 1.0 x 105 Pa and Vf = 40.0 cm3. Friction between the projectile and the launch tube is negligible. (a) If the projectile is launched into a vacuum, what is the speed of the projectile as it leaves the launch tube? (b) If instead the projectile is launched into air at a pressure of 1.0 x 105 Pa, what fraction of the work done by the expanding gas in the tube is spent by the projectile pushing air out of the way as it proceeds down the tube?arrow_forward
- Five bicyclists are riding at the following speeds: 5.4 m/s, 5.7 m/s, 5.8 m/s, 6.0 m/s, and 6.5 m/s. (a) What is their average speed? (b) What is their rms speed?arrow_forwardThe plunger of a syringe has an internal diameter of 1.0 cm and the end of the needle has an internal diameter of 0.35 mm. A practitioner lightly squeezes the plunger, but no serum is emitted by the needle into a vein. So the practitioner gradually increases the squeezing force that she exerts on the plunger such that serum begins to be emitted from the needle into the vein. Assuming no surface tension or friction, what is the minimum squeezing force that the practitioner applies to the plunger in order that serum begins to be emitted from the needle into the vein? Take the pressure of blood in the vein to be 20 mmHg above that of atmospheric pressure. 0.70 N 3.3 N 0.21 N 0.24 N 1.4 N 17Narrow_forwardWater at 15°C is to be pumped from a reservoir (zA = 2 m) to another reservoir at a higher elevation (zB = 9 m) through two 25-m-long plastic pipes connected in parallel. The diameters of the two pipes are 3 cm and 5 cm. Water is to be pumped by a 68 percent efficient motor–pump unit that draws 8 kW of electric power during operation. The minor losses and the head loss in the pipes that connect the parallel pipes to the two reservoirs are considered to be negligible. Determine the total flow rate between the reservoirs and the flow rates through each of the parallel pipes.arrow_forward
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