/*! 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 57 Old Faithful geyser in Yellowsto... [FREE SOLUTION] | 91影视

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Old Faithful geyser in Yellowstone Park erupts at approximately 1-hour intervals, and the height of the fountain reaches \(40.0 \mathrm{~m}\) (Fig. P9.57). (a) Consider the rising stream as a series of separate drops. Analyze the free-fall motion of one of the drops to determine the speed at which the water leaves the ground. (b) Treat the rising stream as an ideal fluid in streamline flow. Use Bernoulli's equation to determine the speed of the water as it leaves ground level. (c) What is the pressure (above atmospheric pressure) in the heated underground chamber \(175 \mathrm{~m}\) below the vent? You may assume the chamber is large compared with the geyser vent.

Short Answer

Expert verified
The speed at which water leaves the ground is found to be approximately \( 28 m/s \). The speed of water at ground level using Bernoulli's equation is found to be the same, confirming the kinematics calculation. The pressure in the heated underground chamber is found to be approximately \( 1.71 x 10^6 Pa \) above the atmospheric pressure.

Step by step solution

01

Finding the speed at which water leaves the ground

Using the kinematic equation \( v^2 = u^2 + 2gs \), where \( u = 0 m/s\) (initial velocity), \( g = 9.8 m/s^2 \) (acceleration due to gravity) and \( s = 40.0m \) (height of fountain), find the final velocity \( v \).
02

Using Bernoulli's equation to determine the speed of the water at ground level

Bernoulli鈥檚 equation between the top of geyser and the ground is written as \( P_1 + \frac{1}{2}蟻v_1^2 + 蟻gh_1 = P_2 + \frac{1}{2}蟻v_2^2 + 蟻gh_2\). Since \( v_1 = 0 \) (velocity at the top of geyser), \( P_1 = P_2 \) (pressure at the top and bottom are equal and can be taken as atmospheric pressure), \( h_1 = 40 m \) (height of geyser), \( h_2 = 0 \) (height at the bottom), and \( 蟻 \) is the density of water. Solving the equation will give the value of \( v_2 \) (velocity at the bottom).
03

Calculating the pressure in the heated underground chamber

The pressure difference between the underground chamber and the surface is due to the weight of the column of the water above it. It can be calculated using the equation \( 螖P = 蟻gh \), where \( h = 175 m \), \( 蟻 \) is the density of water and \( g \) is the acceleration due to gravity. This will give the pressure difference above the atmospheric pressure.

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Key Concepts

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

Kinematic Equations
Kinematic equations play a crucial role in solving objects' motion problems such as determining the velocity of water leaving the ground in the geyser problem. These equations help describe the motion of an object without knowing the forces involved. The primary kinematic equation used in this scenario is:\[ v^2 = u^2 + 2gs \]Where:
  • \( v \) is the final velocity of the water just before it starts its descent.
  • \( u \) is the initial velocity, which in this case is 0 \( m/s \) since the water starts from rest.
  • \( g \) is the acceleration due to gravity, \( 9.8 m/s^2 \).
  • \( s \) is the height reached by the geyser, which is 40 meters.
By substituting these values into the equation, you can solve for the final velocity \( v \). This velocity is crucial for understanding how the water behaves as it ascends and begins to fall back to the ground.
Bernoulli's Equation
Bernoulli's equation is essential for understanding the behavior of fluids in motion, such as the water shooting upwards from Old Faithful geyser. It is expressed as:\[ P_1 + \frac{1}{2}蟻v_1^2 + 蟻gh_1 = P_2 + \frac{1}{2}蟻v_2^2 + 蟻gh_2 \]The terms in Bernoulli's equation explain the balance of energy in a fluid stream:
  • \( P_1, P_2 \) are the pressures at the top and bottom.
  • \( 蟻 \) is the fluid density, in this case, water.
  • \( v_1, v_2 \) are the fluid velocities at the top and base of the geyser.
  • \( h_1, h_2 \) are heights above a reference level.
For this problem, it is assumed that the velocity at the top of the geyser \( v_1 \) is 0, the pressures \( P_1 \) and \( P_2 \) can be taken as equal since both points are atmospheric. Solve Bernoulli's equation to find \( v_2 \), the speed of water leaving ground level. This speed is identical to what we found using kinematic equations, showing the harmony of physics in nature.
Pressure Calculation
Pressure calculations help us determine the pressure in the heated underground chamber contributing to the geyser's eruption. The equation needed here is derived from the concept that the pressure difference \( \Delta P \) is due to the weight of the water column:\[ \Delta P = 蟻gh \]Where:
  • \( \Delta P \) is the pressure above atmospheric pressure.
  • \( 蟻 \) is the density of water.
  • \( g \) is the acceleration due to gravity, which is \( 9.8 m/s^2 \).
  • \( h \) is the depth of the underground chamber, 175 meters below the surface.
By solving this equation, one can find how much higher the pressure in the underground chamber is compared to the atmospheric pressure, aiding in understanding the force that pushes water up through the geyser vent.

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Most popular questions from this chapter

(a) Calculate the absolute pressure at the bottom of a fresh-water lake at a depth of \(27.5 \mathrm{~m}\). Assume the density of the water is \(1.00 \times 10^{3} \mathrm{~kg} / \mathrm{m}^{3}\) and the air above is at a pressure of \(101.3 \mathrm{kPa}\). (b) What force is exerted by the water on the window of an underwater vehicle at this depth if the window is circular and has a diameter of \(35.0 \mathrm{~cm}\) ?

A \(200-\mathrm{kg}\) load is hung on a wire of length \(4.00 \mathrm{~m}\), cross-sectional area \(0.200 \times 10^{-4} \mathrm{~m}^{2}\), and Young's modulus \(8.00 \times 10^{10} \mathrm{~N} / \mathrm{m}^{2}\). What is its increase in length?

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