/*! 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 64 A gas fills the right portion of... [FREE SOLUTION] | 91Ó°ÊÓ

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A gas fills the right portion of a horizontal cylinder whose radius is \(5.00 \mathrm{cm} .\) The initial pressure of the gas is \(1.01 \times 10^{5} \mathrm{Pa} .\) A frictionless movable piston separates the gas from the left portion of the cylinder, which is evacuated and contains an ideal spring, as the drawing shows. The piston is initially held in place by a pin. The spring is initially unstrained, and the length of the gas-filled portion is \(20.0 \mathrm{cm} .\) When the pin is removed and the gas is allowed to expand, the length of the gas-filled chamber doubles. The initial and final temperatures are equal. Determine the spring constant of the spring.

Short Answer

Expert verified
The spring constant is 1985 N/m.

Step by step solution

01

Understand the Problem

We need to determine the spring constant of a spring. Initially, a gas is confined in a portion of a cylinder by a piston. This gas exerts pressure on the piston against an opposing spring. Upon release, the gas expands until the piston reaches a new equilibrium with the spring, doubling the original volume. We must use the initial and final conditions to find the spring constant (\(k\)).
02

Identify Initial and Final Conditions

The initial pressure (\(P_1\)) is \(1.01\times 10^5\;\mathrm{Pa}\), the radius of the cylinder (\(r\)) is \(5\;\mathrm{cm}\), and the initial length (\(L_1\)) of the gas-filled part is \(20\;\mathrm{cm}\). After expansion, this length doubles to \(L_2 = 40\;\mathrm{cm}\). Since the temperature is constant, Boyle's Law (\(P_1V_1 = P_2V_2\)) is applicable. The area of the cylinder's cross-section \(A = \pi r^2\).
03

Calculate Initial Volume

The initial volume \(V_1\) of the gas is given by \(V_1 = A \times L_1 = \pi \times (0.05)^2 \times 0.20 = 1.57 \times 10^{-3} \;\mathrm{m}^3\).
04

Calculate Final Volume

The final volume \(V_2\) is twice that of the initial volume, as the length doubles, so \(V_2 = 2 \times V_1 = 3.14 \times 10^{-3}\;\mathrm{m}^3\).
05

Apply Boyle's Law

We apply Boyle's Law: \(P_1V_1 = P_2V_2\), substituting the known values: \(1.01 \times 10^5 \times 1.57 \times 10^{-3} = P_2 \times 3.14 \times 10^{-3}\). Solving for \(P_2\) yields \(P_2 = 5.05 \times 10^4\;\mathrm{Pa}\).
06

Calculate Change in Pressure

The change in pressure \(\Delta P\) is \(P_1 - P_2 = 1.01 \times 10^5 - 5.05 \times 10^4 = 5.05 \times 10^4 \;\mathrm{Pa}\).
07

Calculate Force by Spring

The force exerted by the spring is given by \(F = \Delta P \times A = (5.05 \times 10^4) \times (\pi \times (0.05)^2) = 397\;\mathrm{N}\).
08

Apply Hooke's Law to Find Spring Constant

Hooke's Law states that \(F = k \times x\), where \(x\) is the change in length. Since the gas-filled chamber length doubles, \(x = L_2 - L_1 = 0.20 \;\mathrm{m}\). Therefore, \(k = \frac{F}{x} = \frac{397}{0.20} = 1985\;\mathrm{N/m}\).

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Key Concepts

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

Boyle's Law
Boyle's Law is a fundamental principle in physics that describes the inverse relationship between the pressure and volume of a fixed amount of gas, provided the temperature remains constant. It is typically expressed as \(P_1V_1 = P_2V_2\). This means that the product of the initial pressure \(P_1\) and volume \(V_1\) equals the product of the final pressure \(P_2\) and volume \(V_2\).
When you have a gas enclosed in a space and its volume is reduced, its pressure increases, provided the temperature does not change. Conversely, if the volume increases, the pressure decreases. This principle is evident in the exercise where the volume of gas doubles and, according to Boyle's Law, the pressure reduces to maintain the equality of the product.
Understanding Boyle's Law is crucial in this context because it allows us to describe how the nonmoveable piston achieves equilibrium when the spring and gas collaborate. By noting the relationship between the changing volumes and pressures, you can start determining unknown quantities, such as the spring constant in the provided scenario.
Piston and Cylinder System
A piston and cylinder system is commonly used to contain gas and measure its physical changes or work potential. In this exercise, the system includes a cylinder with a movable piston that separates the gas from an opposing spring. The piston's radius and position determine the initial volume of the gas chamber.
The system's movement is constrained by the balance of forces exerted by the gas pressure and the spring force.
  • The initial gas volume is limited by the piston's position held by a pin.
  • When the pin is removed, the gas expands, moving the piston and compressing the spring.
This setup allows for easy observation of gas laws in action, such as Boyle's Law, which relates to the pressure and volume created when the piston moves. By analyzing the piston's impacts on gas and spring dynamics, we gain insights into how interconnected these systems are, and how changes in one affect the other.
For engineering, physics, and chemistry students, grasping the functioning of piston and cylinder systems is essential for understanding real-world applications like engines and hydraulic systems.
Ideal Gas Law
The Ideal Gas Law is an equation of state for an ideal gas. It is typically represented as \(PV = nRT\), where:
  • \(P\) stands for pressure
  • \(V\) is the volume
  • \(n\) is the number of moles of gas
  • \(R\) is the ideal gas constant
  • \(T\) is the temperature in Kelvin
Although the Ideal Gas Law provides a broad description applicable to many gaseous systems, it is particularly useful when you consider a system where temperature and the amount of gas remain constant. In our exercise, even though the volume and pressure changed when the pin was removed, the problem stated that the temperature remained constant.
This condition simplified our calculations since the product \(nRT\) remains a constant value, effectively allowing us to use Boyle’s Law instead. Understanding the Ideal Gas Law is crucial for considering how gas properties alter when environmental parameters vary. It bridges the behavior of real gases to theoretical predictions, assisting in calculating unknown parameters like spring constants, as was necessary in our problem.

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Most popular questions from this chapter

An ideal gas at \(15.5^{\circ} \mathrm{C}\) and a pressure of \(1.72 \times 10^{5} \mathrm{Pa}\) occupies a volume of \(2.81 \mathrm{m}^{3} .\) (a) How many moles of gas are present? (b) If the volume is raised to \(4.16 \mathrm{m}^{3}\) and the temperature raised to \(28.2^{\circ} \mathrm{C}\), what will be the pressure of the gas?

Initially, the translational rms speed of a molecule of an ideal gas is \(463 \mathrm{m} / \mathrm{s}\). The pressure and volume of this gas are kept constant, while the number of molecules is doubled. What is the final translational rms speed of the molecules?

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When a gas is diffusing through air in a diffusion channel, the diffusion rate is the number of gas atoms per second diffusing from one end of the channel to the other end. The faster the atoms move, the greater is the diffusion rate, so the diffusion rate is proportional to the rms speed of the atoms. The atomic mass of ideal gas \(\mathrm{A}\) is \(1.0 \mathrm{u}\), and that of ideal gas \(\mathrm{B}\) is \(2.0 \mathrm{u}\). For diffusion through the same channel under the same conditions, find the ratio of the diffusion rate of gas \(A\) to the diffusion rate of gas B.

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