/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 8 The drain plug in a bathtub is d... [FREE SOLUTION] | 91Ó°ÊÓ

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The drain plug in a bathtub is designed to seal properly when there is a 0.05 psi pressure applied to it. How deep must the water be in the tub for the plug to seal?

Short Answer

Expert verified
The water depth must be approximately 0.035 meters (or 3.5 cm) for the plug to seal.

Step by step solution

01

Understanding Pressure

Pressure is defined as the force per unit area. When dealing with fluids, pressure at a depth is given by the formula: \( P = \rho g h \), where \( P \) is the pressure, \( \rho \) is the density of the fluid (water in this case), \( g \) is the acceleration due to gravity, and \( h \) is the height (or depth) of the fluid above the object. In this problem, we want the pressure \( P \) to be at least 0.05 psi.
02

Converting Units

The given pressure is 0.05 psi. To use the pressure formula, we need to convert psi to pascals (Pa) because the standard units for density (kg/m³) and acceleration due to gravity (m/s²) are SI units. Remember, 1 psi is 6894.76 pascals. So, \( 0.05 \) psi is \( 0.05 \times 6894.76 \approx 344.738 \) pascals.
03

Setting Up the Formula

Now, set the equation \( \rho g h = 344.738 \). We know \( \rho \), the density of water, is approximately 1000 kg/m³, and \( g \), the acceleration due to gravity, is approximately 9.81 m/s². Substitute these values into the equation, \( 1000 \times 9.81 \times h = 344.738 \).
04

Solving for Depth

Solve the equation for \( h \): \( h = \frac{344.738}{1000 \times 9.81} \approx \frac{344.738}{9810} \approx 0.035 \) meters. This tells us that the required depth of water for the plug to seal is approximately 0.035 meters.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Pressure Unit Conversion
Understanding pressure unit conversion is crucial when dealing with fluid mechanics. There are many units to express pressure, such as psi (pounds per square inch) and pascals (Pa). However, for most scientific calculations, using SI units like pascals is preferred. Here’s why: Standard International (SI) units allow us to integrate different measurements seamlessly. The conversion between psi and pascals is straightforward once you know the conversion factor.
  • 1 psi is equal to 6894.76 pascals.
When performing calculations involving forces and areas in different units, accuracy relies on precise conversion. For instance, to convert 0.05 psi to pascals, you multiply by the conversion factor: \[0.05 imes 6894.76 = 344.738\] This conversion ensures that your pressure calculations in the formula will be coherent with the units of density and gravity, which are in kg/m³ and m/s² respectively.
Fluid Depth Calculation
Calculating the depth of fluid required to achieve a certain pressure at a point is a fascinating application of pressure concepts. In our exercise, we aim to find the depth at which water applies a pressure of 0.05 psi on the drain plug to ensure it seals properly. the Pressure Given the equation for pressure in fluids: \[P = \rho g h\] where:
  • \(P\) is the pressure,
  • \(\rho\) is the density of the fluid (about 1000 kg/m³ for water),
  • \(g\) is the acceleration due to gravity (9.81 m/s²), and
  • \(h\) is the fluid depth above the point of measurement.
The goal is to solve for \(h\) when you know \(P\) after converting to pascals. By rearranging the formula, you get: \[h = \frac{P}{\rho g}\] Substituting the given values produces: \[h = \frac{344.738}{1000 \, \times \, 9.81} \approx 0.035 \, \text{meters}\] Thus, the water needs to be about 0.035 meters deep.
Pressure Formula for Fluids
The pressure formula for fluids helps you calculate how deep a liquid must be to exert a specific amount of pressure at a particular point. This principle is prevalent in many real-world scenarios, including engineering and environmental science. The general formula to determine pressure from fluid depth is: \[P = \rho g h\] This equation works by considering three main factors of fluid pressure:
  • The density of the fluid (\(\rho\)), which is the mass per unit volume.
  • The gravitational acceleration (\(g\)), usually approximated as 9.81 m/s² on Earth.
  • The depth of the fluid (\(h\)), representing the height of the liquid column above the point where pressure is measured.
This formula indicates that pressure increases with an increase in either the fluid depth or density. Understanding this relationship is crucial for tasks involving buoyancy, hydraulics, and ensuring mechanisms like the bathtub drain plug function correctly by sealing at a required pressure.

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Most popular questions from this chapter

A 0.3 -m-diameter pipe is connected to a 0.02 -m-diameter pipe and both are rigidly held in place. Both pipes are horizontal with pistons at each end. If the space between the pistons is filled with water, what force will have to be applied to the larger piston to balance a force of \(80 \mathrm{N}\) applied to the smaller piston? Neglect friction.

For the great depths that may be encountered in the ocean the compressibility of seawater may become an important consideration. (a) Assume that the bulk modulus for seawater is constant and derive a relationship between pressure and depth which takes into account the change in fluid density with depth. (b) Make use of part (a) to determine the pressure at a depth of \(6 \mathrm{km}\) assuming seawater has a bulk modulus of \(2.3 \times 10^{9} \mathrm{Pa}\) and a density of \(1030 \mathrm{kg} / \mathrm{m}^{3}\) at the surface. Compare this result with that obtained by assuming a constant density of \(1030 \mathrm{kg} / \mathrm{m}^{3}\)

You partially fill a glass with water, place an index card on top of the glass, and then turn the glass upside down while holding the card in place. You can then remove your hand from the card and the card remains in place, holding the water in the glass. Explain how this works.

A barometric pressure of 29.4 in. Hg corresponds to what value of atmospheric pressure in psia, and in pascals?

2.3 An unknown immiscible liquid seeps into the bottom of an open oil tank. Some measurements indicate that the depth of the unknown liquid is \(1.5 \mathrm{m}\) and the depth of the oil (specific weight \(=8.5 \mathrm{kN} / \mathrm{m}^{3}\) ) floating on top is \(5.0 \mathrm{m}\). A pressure gage connected to the bottom of the tank reads 65 kPa. What is the specific gravity of the unknown liquid?

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