{"id":2114,"date":"2014-12-11T02:29:29","date_gmt":"2014-12-11T02:29:29","guid":{"rendered":"https:\/\/courses.candelalearning.com\/colphysics\/?post_type=chapter&#038;p=2114"},"modified":"2016-11-03T18:22:48","modified_gmt":"2016-11-03T18:22:48","slug":"11-5-pascals-principle","status":"publish","type":"chapter","link":"https:\/\/courses.lumenlearning.com\/suny-physics\/chapter\/11-5-pascals-principle\/","title":{"raw":"Pascal\u2019s Principle","rendered":"Pascal\u2019s Principle"},"content":{"raw":"<div>\r\n<div class=\"textbox learning-objectives\">\r\n<h3>Learning Objectives<\/h3>\r\nBy the end of this section, you will be able to:\r\n<div>\r\n<ul>\r\n\t<li>Define pressure.<\/li>\r\n\t<li>State Pascal\u2019s principle.<\/li>\r\n\t<li>Understand applications of Pascal\u2019s principle.<\/li>\r\n\t<li>Derive relationships between forces in a hydraulic system.<\/li>\r\n<\/ul>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<em> Pressure<\/em> is defined as force per unit area. Can pressure be increased in a fluid by pushing directly on the fluid? Yes, but it is much easier if the fluid is enclosed. The heart, for example, increases blood pressure by pushing directly on the blood in an enclosed system (valves closed in a chamber). If you try to push on a fluid in an open system, such as a river, the fluid flows away. An enclosed fluid cannot flow away, and so pressure is more easily increased by an applied force. What happens to a pressure in an enclosed fluid? Since atoms in a fluid are free to move about, they transmit the pressure to all parts of the fluid and to the walls of the container. Remarkably, the pressure is transmitted <em>undiminished<\/em>. This phenomenon is called <em> Pascal\u2019s principle<\/em>, because it was first clearly stated by the French philosopher and scientist Blaise Pascal (1623\u20131662): A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.\r\n<div>\r\n<div>\r\n<div class=\"textbox shaded\">\r\n<h3><strong>Pascal\u2019s Principle<\/strong><\/h3>\r\n<div>A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.<\/div>\r\n<\/div>\r\n<\/div>\r\nPascal\u2019s principle, an experimentally verified fact, is what makes pressure so important in fluids. Since a change in pressure is transmitted undiminished in an enclosed fluid, we often know more about pressure than other physical quantities in fluids. Moreover, Pascal\u2019s principle implies that <em>the total pressure in a fluid is the sum of the pressures from different sources<\/em>. We shall find this fact\u2014that pressures add\u2014very useful.\r\n\r\n<\/div>\r\nBlaise Pascal had an interesting life in that he was home-schooled by his father who removed all of the mathematics textbooks from his house and forbade him to study mathematics until the age of 15. This, of course, raised the boy\u2019s curiosity, and by the age of 12, he started to teach himself geometry. Despite this early deprivation, Pascal went on to make major contributions in the mathematical fields of probability theory, number theory, and geometry. He is also well known for being the inventor of the first mechanical digital calculator, in addition to his contributions in the field of fluid statics.\r\n<div>\r\n<div>\r\n<h2>Application of Pascal\u2019s Principle<\/h2>\r\n<\/div>\r\nOne of the most important technological applications of Pascal\u2019s principle is found in a <em>hydraulic system<\/em>, which is an enclosed fluid system used to exert forces. The most common hydraulic systems are those that operate car brakes. Let us first consider the simple hydraulic system shown in Figure 1.\r\n<div>\r\n<div>\r\n<div>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"410\"]<img class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/222\/2014\/12\/20103733\/Figure_12_05_01a.jpg\" alt=\"A small force can be converted into a larger force when pressure is transmitted through liquids in different containers with pistons that are connected.\" width=\"410\" height=\"391\" \/> Figure 1. A typical hydraulic system with two fluid-filled cylinders, capped with pistons and connected by a tube called a hydraulic line. A downward force <strong>F<\/strong><sub>1<\/sub>\u00a0on the left piston creates a pressure that is transmitted undiminished to all parts of the enclosed fluid. This results in an upward force <strong>F<\/strong><sub>2<\/sub> on the right piston that is larger than <strong>F<\/strong><sub>1<\/sub> because the right piston has a larger area.[\/caption]\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n<div>\r\n<div>\r\n<h2>Relationship Between Forces in a Hydraulic System<\/h2>\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nWe can derive a relationship between the forces in the simple hydraulic system shown in Figure 1\u00a0by applying Pascal\u2019s principle. Note first that the two pistons in the system are at the same height, and so there will be no difference in pressure due to a difference in depth. Now the pressure due to <em>F<\/em><sub>1<\/sub> acting on area <em>A<\/em><sub>1<\/sub> is simply\u00a0[latex]{P}_{1}=\\frac{{F}_{1}}{{A}_{1}}\\\\[\/latex], as defined by [latex]P=\\frac{F}{A}\\\\[\/latex]. According to Pascal\u2019s principle, this pressure is transmitted undiminished throughout the fluid and to all walls of the container. Thus, a pressure <em>P<\/em><sub>2<\/sub> is felt at the other piston that is equal to <em>P<\/em><sub>1<\/sub>. That is <em>P<\/em><sub>1\u00a0<\/sub>=\u00a0<em>P<\/em><sub>2<\/sub>. But since\u00a0[latex]{P}_{2}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex], we see that [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]. This equation relates the ratios of force to area in any hydraulic system, providing the pistons are at the same vertical height and that friction in the system is negligible. Hydraulic systems can increase or decrease the force applied to them. To make the force larger, the pressure is applied to a larger area. For example, if a 100-N force is applied to the left cylinder in Figure 1\u00a0and the right one has an area five times greater, then the force out is 500 N. Hydraulic systems are analogous to simple levers, but they have the advantage that pressure can be sent through tortuously curved lines to several places at once.\r\n<div>\r\n<div>\r\n<div class=\"textbox examples\">\r\n<h3>Example 1. Calculating Force of Slave Cylinders: Pascal Puts on the Brakes<\/h3>\r\n<div>\r\n\r\nConsider the automobile hydraulic system shown in Figure 2.\r\n<div>\r\n<div>\r\n<div>\r\n\r\n[caption id=\"\" align=\"aligncenter\" width=\"461\"]<img src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/222\/2014\/12\/20103735\/Figure_12_05_02a.jpg\" alt=\"When the driver applies force on the brake pedal the master cylinder transmits the same pressure to the slave cylinders but results in a larger force due to the larger area of the slave cylinders.\" width=\"461\" height=\"367\" \/> Figure 2. Hydraulic brakes use Pascal\u2019s principle. The driver exerts a force of 100 N on the brake pedal. This force is increased by the simple lever and again by the hydraulic system. Each of the identical slave cylinders receives the same pressure and, therefore, creates the same force output<em> F<\/em><sub>2<\/sub>. The circular cross-sectional areas of the master and slave cylinders are represented by <em>A<\/em><sub>1<\/sub> and <em>A<\/em><sub>2<\/sub>, respectively[\/caption]\r\n\r\nA force of 100 N is applied to the brake pedal, which acts on the cylinder\u2014called the master\u2014through a lever. A force of 500 N is exerted on the master cylinder. (The reader can verify that the force is 500 N using techniques of statics from <a href=\".\/chapter\/9-4-applications-of-statics-including-problem-solving-strategies\/\" target=\"_blank\">Applications of Statics, Including Problem-Solving Strategies<\/a>.) Pressure created in the master cylinder is transmitted to four so-called slave cylinders. The master cylinder has a diameter of 0.500 cm, and each slave cylinder has a diameter of 2.50 cm. Calculate the force <em>F<\/em><sub>2<\/sub> created at each of the slave cylinders.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<h4><strong>Strategy<\/strong><\/h4>\r\nWe are given the force <em>F<\/em><sub>1<\/sub> that is applied to the master cylinder. The cross-sectional areas\u00a0<em>A<\/em><sub>1<\/sub> and <em>A<\/em><sub>2<\/sub> can be calculated from their given diameters. Then [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]\u00a0can be used to find the force <em>F<\/em><sub>2<\/sub>. Manipulate this algebraically to get <em>F<\/em><sub>2<\/sub> on one side and substitute known values:\r\n<h4><strong>Solution<\/strong><\/h4>\r\nPascal\u2019s principle applied to hydraulic systems is given by [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]:\r\n<p style=\"text-align: center;\">[latex]{F}_{2}=\\frac{{A}_{2}}{{A}_{1}}{F}_{1}=\\frac{{\\mathrm{{\\pi r}}_{2}}^{2}}{{\\mathrm{{\\pi r}}_{1}}^{2}}{F}_{1}=\\frac{{\\left(1.25 \\text{ cm}\\right)}^{2}}{{\\left(0.250 \\text{ cm}\\right)}^{2}}\\times \\text{500 N}=1\\text{.}\\text{25}\\times {\\text{10}}^{4}\\text{N}\\\\[\/latex].<\/p>\r\n\r\n<h4><strong>Discussion<\/strong><\/h4>\r\nThis value is the force exerted by each of the four slave cylinders. Note that we can add as many slave cylinders as we wish. If each has a 2.50-cm diameter, each will exert 1.25 \u00d7 10<sup>4<\/sup> N.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\nA simple hydraulic system, such as a simple machine, can increase force but cannot do more work than done on it. Work is force times distance moved, and the slave cylinder moves through a smaller distance than the master cylinder. Furthermore, the more slaves added, the smaller the distance each moves. Many hydraulic systems\u2014such as power brakes and those in bulldozers\u2014have a motorized pump that actually does most of the work in the system. The movement of the legs of a spider is achieved partly by hydraulics. Using hydraulics, a jumping spider can create a force that makes it capable of jumping 25 times its length!\r\n\r\n<\/div>\r\n<div><header>\r\n<div class=\"textbox learning-objectives\">\r\n<h3>Making Connections: Conservation of Energy<\/h3>\r\n<header><\/header><section>Conservation of energy applied to a hydraulic system tells us that the system cannot do more work than is done on it. Work transfers energy, and so the work output cannot exceed the work input. Power brakes and other similar hydraulic systems use pumps to supply extra energy when needed.<\/section><\/div>\r\n<\/header><\/div>\r\n<\/div>\r\n<h2>Section Summary<\/h2>\r\n<ul>\r\n\t<li>Pressure is force per unit area.<\/li>\r\n\t<li>A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.<\/li>\r\n\t<li>A hydraulic system is an enclosed fluid system used to exert forces.<\/li>\r\n<\/ul>\r\n<section>\r\n<div class=\"textbox key-takeaways\">\r\n<h3>Conceptual Questions<\/h3>\r\n<div>\r\n<div>\r\n\r\n1. Suppose the master cylinder in a hydraulic system is at a greater height than the slave cylinder. Explain how this will affect the force produced at the slave cylinder.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/section><section>\r\n<div class=\"textbox exercises\">\r\n<h3>Problems &amp; Exercises<\/h3>\r\n<div>\r\n<div>\r\n\r\n1. How much pressure is transmitted in the hydraulic system considered in Example 1? Express your answer in pascals and in atmospheres.\r\n\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\n2. What force must be exerted on the master cylinder of a hydraulic lift to support the weight of a 2000-kg car (a large car) resting on the slave cylinder? The master cylinder has a 2.00-cm diameter and the slave has a 24.0-cm diameter.\r\n\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\n3. A crass host pours the remnants of several bottles of wine into a jug after a party. He then inserts a cork with a 2.00-cm diameter into the bottle, placing it in direct contact with the wine. He is amazed when he pounds the cork into place and the bottom of the jug (with a 14.0-cm diameter) breaks away. Calculate the extra force exerted against the bottom if he pounded the cork with a 120-N force.\r\n\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\n4. A certain hydraulic system is designed to exert a force 100 times as large as the one put into it. (a) What must be the ratio of the area of the slave cylinder to the area of the master cylinder? (b) What must be the ratio of their diameters? (c) By what factor is the distance through which the output force moves reduced relative to the distance through which the input force moves? Assume no losses to friction.\r\n\r\n<\/div>\r\n<\/div>\r\n<div>\r\n<div>\r\n\r\n(5. a) Verify that work input equals work output for a hydraulic system assuming no losses to friction. Do this by showing that the distance the output force moves is reduced by the same factor that the output force is increased. Assume the volume of the fluid is constant. (b) What effect would friction within the fluid and between components in the system have on the output force? How would this depend on whether or not the fluid is moving?\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>\r\n<\/section>\r\n<div>\r\n<h2>Glossary<\/h2>\r\n<dl><dt>Pascal\u2019s Principle:<\/dt><dd>a change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container<\/dd><\/dl>\r\n<div class=\"textbox exercises\">\r\n<h3>Selected Solutions to Problems &amp; Exercises<\/h3>\r\n1. 2.55 \u00d7 10<sup>7<\/sup> Pa; or 251 atm\r\n\r\n3. 5.76 \u00d7 10<sup>3<\/sup> extra force\r\n\r\n5.\u00a0(a) [latex]V={d}_{\\text{i}}{A}_{\\text{i}}={d}_{\\text{o}}{A}_{\\text{o}}\\Rightarrow {d}_{\\text{o}}={d}_{\\text{i}}\\left(\\frac{{A}_{\\text{i}}}{{A}_{\\text{o}}}\\right)\\\\[\/latex].\r\n<div>\r\n\r\nNow, using equation:\r\n<div style=\"text-align: center;\">[latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\Rightarrow {F}_{\\text{o}}={F}_{\\text{i}}\\left(\\frac{{A}_{\\text{o}}}{{A}_{\\text{i}}}\\right)\\\\[\/latex].<\/div>\r\nFinally,\r\n<div style=\"text-align: center;\">[latex]{W}_{\\text{o}}={F}_{\\text{o}}{d}_{\\text{o}}=\\left(\\frac{{F}_{\\text{i}}{A}_{\\text{o}}}{{A}_{\\text{i}}}\\right)\\left(\\frac{{d}_{\\text{i}}{A}_{\\text{i}}}{{A}_{\\text{o}}}\\right)={F}_{\\text{i}}{d}_{\\text{i}}={W}_{\\text{i}}\\\\[\/latex].<\/div>\r\n&nbsp;\r\n\r\nIn other words, the work output equals the work input.\r\n\r\n(b) If the system is not moving, friction would not play a role. With friction, we know there are losses, so that [latex]{W}_{\\text{out}}={W}_{\\text{in}}-{W}_{\\text{f}}\\\\[\/latex]; therefore, the work output is less than the work input. In other words, with friction, you need to push harder on the input piston than was calculated for the nonfriction case.\r\n\r\n<\/div>\r\n<\/div>\r\n<\/div>","rendered":"<div>\n<div class=\"textbox learning-objectives\">\n<h3>Learning Objectives<\/h3>\n<p>By the end of this section, you will be able to:<\/p>\n<div>\n<ul>\n<li>Define pressure.<\/li>\n<li>State Pascal\u2019s principle.<\/li>\n<li>Understand applications of Pascal\u2019s principle.<\/li>\n<li>Derive relationships between forces in a hydraulic system.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<p><em> Pressure<\/em> is defined as force per unit area. Can pressure be increased in a fluid by pushing directly on the fluid? Yes, but it is much easier if the fluid is enclosed. The heart, for example, increases blood pressure by pushing directly on the blood in an enclosed system (valves closed in a chamber). If you try to push on a fluid in an open system, such as a river, the fluid flows away. An enclosed fluid cannot flow away, and so pressure is more easily increased by an applied force. What happens to a pressure in an enclosed fluid? Since atoms in a fluid are free to move about, they transmit the pressure to all parts of the fluid and to the walls of the container. Remarkably, the pressure is transmitted <em>undiminished<\/em>. This phenomenon is called <em> Pascal\u2019s principle<\/em>, because it was first clearly stated by the French philosopher and scientist Blaise Pascal (1623\u20131662): A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.<\/p>\n<div>\n<div>\n<div class=\"textbox shaded\">\n<h3><strong>Pascal\u2019s Principle<\/strong><\/h3>\n<div>A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.<\/div>\n<\/div>\n<\/div>\n<p>Pascal\u2019s principle, an experimentally verified fact, is what makes pressure so important in fluids. Since a change in pressure is transmitted undiminished in an enclosed fluid, we often know more about pressure than other physical quantities in fluids. Moreover, Pascal\u2019s principle implies that <em>the total pressure in a fluid is the sum of the pressures from different sources<\/em>. We shall find this fact\u2014that pressures add\u2014very useful.<\/p>\n<\/div>\n<p>Blaise Pascal had an interesting life in that he was home-schooled by his father who removed all of the mathematics textbooks from his house and forbade him to study mathematics until the age of 15. This, of course, raised the boy\u2019s curiosity, and by the age of 12, he started to teach himself geometry. Despite this early deprivation, Pascal went on to make major contributions in the mathematical fields of probability theory, number theory, and geometry. He is also well known for being the inventor of the first mechanical digital calculator, in addition to his contributions in the field of fluid statics.<\/p>\n<div>\n<div>\n<h2>Application of Pascal\u2019s Principle<\/h2>\n<\/div>\n<p>One of the most important technological applications of Pascal\u2019s principle is found in a <em>hydraulic system<\/em>, which is an enclosed fluid system used to exert forces. The most common hydraulic systems are those that operate car brakes. Let us first consider the simple hydraulic system shown in Figure 1.<\/p>\n<div>\n<div>\n<div>\n<div style=\"width: 420px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" class=\"\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/222\/2014\/12\/20103733\/Figure_12_05_01a.jpg\" alt=\"A small force can be converted into a larger force when pressure is transmitted through liquids in different containers with pistons that are connected.\" width=\"410\" height=\"391\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 1. A typical hydraulic system with two fluid-filled cylinders, capped with pistons and connected by a tube called a hydraulic line. A downward force <strong>F<\/strong><sub>1<\/sub>\u00a0on the left piston creates a pressure that is transmitted undiminished to all parts of the enclosed fluid. This results in an upward force <strong>F<\/strong><sub>2<\/sub> on the right piston that is larger than <strong>F<\/strong><sub>1<\/sub> because the right piston has a larger area.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<div>\n<div>\n<div>\n<div>\n<h2>Relationship Between Forces in a Hydraulic System<\/h2>\n<\/div>\n<\/div>\n<\/div>\n<p>We can derive a relationship between the forces in the simple hydraulic system shown in Figure 1\u00a0by applying Pascal\u2019s principle. Note first that the two pistons in the system are at the same height, and so there will be no difference in pressure due to a difference in depth. Now the pressure due to <em>F<\/em><sub>1<\/sub> acting on area <em>A<\/em><sub>1<\/sub> is simply\u00a0[latex]{P}_{1}=\\frac{{F}_{1}}{{A}_{1}}\\\\[\/latex], as defined by [latex]P=\\frac{F}{A}\\\\[\/latex]. According to Pascal\u2019s principle, this pressure is transmitted undiminished throughout the fluid and to all walls of the container. Thus, a pressure <em>P<\/em><sub>2<\/sub> is felt at the other piston that is equal to <em>P<\/em><sub>1<\/sub>. That is <em>P<\/em><sub>1\u00a0<\/sub>=\u00a0<em>P<\/em><sub>2<\/sub>. But since\u00a0[latex]{P}_{2}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex], we see that [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]. This equation relates the ratios of force to area in any hydraulic system, providing the pistons are at the same vertical height and that friction in the system is negligible. Hydraulic systems can increase or decrease the force applied to them. To make the force larger, the pressure is applied to a larger area. For example, if a 100-N force is applied to the left cylinder in Figure 1\u00a0and the right one has an area five times greater, then the force out is 500 N. Hydraulic systems are analogous to simple levers, but they have the advantage that pressure can be sent through tortuously curved lines to several places at once.<\/p>\n<div>\n<div>\n<div class=\"textbox examples\">\n<h3>Example 1. Calculating Force of Slave Cylinders: Pascal Puts on the Brakes<\/h3>\n<div>\n<p>Consider the automobile hydraulic system shown in Figure 2.<\/p>\n<div>\n<div>\n<div>\n<div style=\"width: 471px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/s3-us-west-2.amazonaws.com\/courses-images-archive-read-only\/wp-content\/uploads\/sites\/222\/2014\/12\/20103735\/Figure_12_05_02a.jpg\" alt=\"When the driver applies force on the brake pedal the master cylinder transmits the same pressure to the slave cylinders but results in a larger force due to the larger area of the slave cylinders.\" width=\"461\" height=\"367\" \/><\/p>\n<p class=\"wp-caption-text\">Figure 2. Hydraulic brakes use Pascal\u2019s principle. The driver exerts a force of 100 N on the brake pedal. This force is increased by the simple lever and again by the hydraulic system. Each of the identical slave cylinders receives the same pressure and, therefore, creates the same force output<em> F<\/em><sub>2<\/sub>. The circular cross-sectional areas of the master and slave cylinders are represented by <em>A<\/em><sub>1<\/sub> and <em>A<\/em><sub>2<\/sub>, respectively<\/p>\n<\/div>\n<p>A force of 100 N is applied to the brake pedal, which acts on the cylinder\u2014called the master\u2014through a lever. A force of 500 N is exerted on the master cylinder. (The reader can verify that the force is 500 N using techniques of statics from <a href=\".\/chapter\/9-4-applications-of-statics-including-problem-solving-strategies\/\" target=\"_blank\">Applications of Statics, Including Problem-Solving Strategies<\/a>.) Pressure created in the master cylinder is transmitted to four so-called slave cylinders. The master cylinder has a diameter of 0.500 cm, and each slave cylinder has a diameter of 2.50 cm. Calculate the force <em>F<\/em><sub>2<\/sub> created at each of the slave cylinders.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<h4><strong>Strategy<\/strong><\/h4>\n<p>We are given the force <em>F<\/em><sub>1<\/sub> that is applied to the master cylinder. The cross-sectional areas\u00a0<em>A<\/em><sub>1<\/sub> and <em>A<\/em><sub>2<\/sub> can be calculated from their given diameters. Then [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]\u00a0can be used to find the force <em>F<\/em><sub>2<\/sub>. Manipulate this algebraically to get <em>F<\/em><sub>2<\/sub> on one side and substitute known values:<\/p>\n<h4><strong>Solution<\/strong><\/h4>\n<p>Pascal\u2019s principle applied to hydraulic systems is given by [latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\\\[\/latex]:<\/p>\n<p style=\"text-align: center;\">[latex]{F}_{2}=\\frac{{A}_{2}}{{A}_{1}}{F}_{1}=\\frac{{\\mathrm{{\\pi r}}_{2}}^{2}}{{\\mathrm{{\\pi r}}_{1}}^{2}}{F}_{1}=\\frac{{\\left(1.25 \\text{ cm}\\right)}^{2}}{{\\left(0.250 \\text{ cm}\\right)}^{2}}\\times \\text{500 N}=1\\text{.}\\text{25}\\times {\\text{10}}^{4}\\text{N}\\\\[\/latex].<\/p>\n<h4><strong>Discussion<\/strong><\/h4>\n<p>This value is the force exerted by each of the four slave cylinders. Note that we can add as many slave cylinders as we wish. If each has a 2.50-cm diameter, each will exert 1.25 \u00d7 10<sup>4<\/sup> N.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<p>A simple hydraulic system, such as a simple machine, can increase force but cannot do more work than done on it. Work is force times distance moved, and the slave cylinder moves through a smaller distance than the master cylinder. Furthermore, the more slaves added, the smaller the distance each moves. Many hydraulic systems\u2014such as power brakes and those in bulldozers\u2014have a motorized pump that actually does most of the work in the system. The movement of the legs of a spider is achieved partly by hydraulics. Using hydraulics, a jumping spider can create a force that makes it capable of jumping 25 times its length!<\/p>\n<\/div>\n<div>\n<header>\n<div class=\"textbox learning-objectives\">\n<h3>Making Connections: Conservation of Energy<\/h3>\n<\/div>\n<\/header>\n<header><\/header>\n<section>Conservation of energy applied to a hydraulic system tells us that the system cannot do more work than is done on it. Work transfers energy, and so the work output cannot exceed the work input. Power brakes and other similar hydraulic systems use pumps to supply extra energy when needed.<\/section>\n<\/div>\n<\/div>\n<h2>Section Summary<\/h2>\n<ul>\n<li>Pressure is force per unit area.<\/li>\n<li>A change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container.<\/li>\n<li>A hydraulic system is an enclosed fluid system used to exert forces.<\/li>\n<\/ul>\n<section>\n<div class=\"textbox key-takeaways\">\n<h3>Conceptual Questions<\/h3>\n<div>\n<div>\n<p>1. Suppose the master cylinder in a hydraulic system is at a greater height than the slave cylinder. Explain how this will affect the force produced at the slave cylinder.<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n<section>\n<div class=\"textbox exercises\">\n<h3>Problems &amp; Exercises<\/h3>\n<div>\n<div>\n<p>1. How much pressure is transmitted in the hydraulic system considered in Example 1? Express your answer in pascals and in atmospheres.<\/p>\n<\/div>\n<\/div>\n<div>\n<div>\n<p>2. What force must be exerted on the master cylinder of a hydraulic lift to support the weight of a 2000-kg car (a large car) resting on the slave cylinder? The master cylinder has a 2.00-cm diameter and the slave has a 24.0-cm diameter.<\/p>\n<\/div>\n<\/div>\n<div>\n<div>\n<p>3. A crass host pours the remnants of several bottles of wine into a jug after a party. He then inserts a cork with a 2.00-cm diameter into the bottle, placing it in direct contact with the wine. He is amazed when he pounds the cork into place and the bottom of the jug (with a 14.0-cm diameter) breaks away. Calculate the extra force exerted against the bottom if he pounded the cork with a 120-N force.<\/p>\n<\/div>\n<\/div>\n<div>\n<div>\n<p>4. A certain hydraulic system is designed to exert a force 100 times as large as the one put into it. (a) What must be the ratio of the area of the slave cylinder to the area of the master cylinder? (b) What must be the ratio of their diameters? (c) By what factor is the distance through which the output force moves reduced relative to the distance through which the input force moves? Assume no losses to friction.<\/p>\n<\/div>\n<\/div>\n<div>\n<div>\n<p>(5. a) Verify that work input equals work output for a hydraulic system assuming no losses to friction. Do this by showing that the distance the output force moves is reduced by the same factor that the output force is increased. Assume the volume of the fluid is constant. (b) What effect would friction within the fluid and between components in the system have on the output force? How would this depend on whether or not the fluid is moving?<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/section>\n<div>\n<h2>Glossary<\/h2>\n<dl>\n<dt>Pascal\u2019s Principle:<\/dt>\n<dd>a change in pressure applied to an enclosed fluid is transmitted undiminished to all portions of the fluid and to the walls of its container<\/dd>\n<\/dl>\n<div class=\"textbox exercises\">\n<h3>Selected Solutions to Problems &amp; Exercises<\/h3>\n<p>1. 2.55 \u00d7 10<sup>7<\/sup> Pa; or 251 atm<\/p>\n<p>3. 5.76 \u00d7 10<sup>3<\/sup> extra force<\/p>\n<p>5.\u00a0(a) [latex]V={d}_{\\text{i}}{A}_{\\text{i}}={d}_{\\text{o}}{A}_{\\text{o}}\\Rightarrow {d}_{\\text{o}}={d}_{\\text{i}}\\left(\\frac{{A}_{\\text{i}}}{{A}_{\\text{o}}}\\right)\\\\[\/latex].<\/p>\n<div>\n<p>Now, using equation:<\/p>\n<div style=\"text-align: center;\">[latex]\\frac{{F}_{1}}{{A}_{1}}=\\frac{{F}_{2}}{{A}_{2}}\\Rightarrow {F}_{\\text{o}}={F}_{\\text{i}}\\left(\\frac{{A}_{\\text{o}}}{{A}_{\\text{i}}}\\right)\\\\[\/latex].<\/div>\n<p>Finally,<\/p>\n<div style=\"text-align: center;\">[latex]{W}_{\\text{o}}={F}_{\\text{o}}{d}_{\\text{o}}=\\left(\\frac{{F}_{\\text{i}}{A}_{\\text{o}}}{{A}_{\\text{i}}}\\right)\\left(\\frac{{d}_{\\text{i}}{A}_{\\text{i}}}{{A}_{\\text{o}}}\\right)={F}_{\\text{i}}{d}_{\\text{i}}={W}_{\\text{i}}\\\\[\/latex].<\/div>\n<p>&nbsp;<\/p>\n<p>In other words, the work output equals the work input.<\/p>\n<p>(b) If the system is not moving, friction would not play a role. With friction, we know there are losses, so that [latex]{W}_{\\text{out}}={W}_{\\text{in}}-{W}_{\\text{f}}\\\\[\/latex]; therefore, the work output is less than the work input. In other words, with friction, you need to push harder on the input piston than was calculated for the nonfriction case.<\/p>\n<\/div>\n<\/div>\n<\/div>\n\n\t\t\t <section class=\"citations-section\" role=\"contentinfo\">\n\t\t\t <h3>Candela Citations<\/h3>\n\t\t\t\t\t <div>\n\t\t\t\t\t\t <div id=\"citation-list-2114\">\n\t\t\t\t\t\t\t <div class=\"licensing\"><div class=\"license-attribution-dropdown-subheading\">CC licensed content, Shared previously<\/div><ul class=\"citation-list\"><li>College Physics. <strong>Authored by<\/strong>: OpenStax College. <strong>Located at<\/strong>: <a target=\"_blank\" href=\"http:\/\/cnx.org\/contents\/031da8d3-b525-429c-80cf-6c8ed997733a\/College_Physics\">http:\/\/cnx.org\/contents\/031da8d3-b525-429c-80cf-6c8ed997733a\/College_Physics<\/a>. <strong>License<\/strong>: <em><a target=\"_blank\" rel=\"license\" href=\"https:\/\/creativecommons.org\/licenses\/by\/4.0\/\">CC BY: Attribution<\/a><\/em>. <strong>License Terms<\/strong>: Located at License<\/li><\/ul><\/div>\n\t\t\t\t\t\t <\/div>\n\t\t\t\t\t <\/div>\n\t\t\t <\/section>","protected":false},"author":1,"menu_order":6,"template":"","meta":{"_candela_citation":"[{\"type\":\"cc\",\"description\":\"College Physics\",\"author\":\"OpenStax College\",\"organization\":\"\",\"url\":\"http:\/\/cnx.org\/contents\/031da8d3-b525-429c-80cf-6c8ed997733a\/College_Physics\",\"project\":\"\",\"license\":\"cc-by\",\"license_terms\":\"Located at License\"}]","CANDELA_OUTCOMES_GUID":"","pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-2114","chapter","type-chapter","status-publish","hentry"],"part":7546,"_links":{"self":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapters\/2114","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":15,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapters\/2114\/revisions"}],"predecessor-version":[{"id":12044,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapters\/2114\/revisions\/12044"}],"part":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/parts\/7546"}],"metadata":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapters\/2114\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/wp\/v2\/media?parent=2114"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/pressbooks\/v2\/chapter-type?post=2114"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/wp\/v2\/contributor?post=2114"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/courses.lumenlearning.com\/suny-physics\/wp-json\/wp\/v2\/license?post=2114"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}