Problem 10

Question

Translate each statement of variation into an equation, and use \(k\) as the constant of variation. The volume \((V)\) of a gas varies directly as the absolute temperature \((T)\) and inversely as the pressure \((P)\).

Step-by-Step Solution

Verified
Answer
The equation is \( V = \frac{kT}{P} \).
1Step 1: Understand the variation types
In this problem, we have both a direct variation and an inverse variation. Volume \( V \) varies directly with absolute temperature \( T \), and varies inversely with pressure \( P \). This means for direct variation, as \( T \) increases, \( V \) increases, and for inverse variation, as \( P \) increases, \( V \) decreases.
2Step 2: Write the composite variation equation
To express \( V \) in terms of direct and inverse variation, we combine both relationships into one equation. The direct variation with \( T \) means \( V = kT \), where \( k \) is a constant. The inverse variation with \( P \) transforms the equation to \( V = \frac{kT}{P} \).
3Step 3: Combine everything into one equation
The final equation that combines the direct variation of \( V \) with \( T \) and the inverse variation with \( P \) is: \[V = \frac{kT}{P}\] This equation represents how the volume of gas is related to temperature and pressure.

Key Concepts

Direct VariationInverse VariationConstant of Variation
Direct Variation
In mathematics, direct variation describes a relationship where two variables change proportionally. If one variable increases, the other does too, and vice versa. This can be expressed with the equation: \( y = kx \). Here, \( y \) is the variable that directly varies with \( x \), and \( k \) is a non-zero constant known as the constant of variation.

Direct variation implies a linear relationship through the origin of a graph. For every unit increase in \( x \), \( y \) increases by \( k \) units. This relationship can often be seen in real-life situations such as distance versus time at constant speed.

When solving problems involving direct variation, you need to:
  • Identify the variables that change together.
  • Determine the constant of variation \( k \).
  • Formulate the direct variation equation \( y = kx \).
These steps help translate a direct variation problem into an understandable mathematical format.
Inverse Variation
Inverse variation occurs when one variable increases while another decreases, maintaining a mathematical balance. In other words, if one variable goes up, the other goes down such that their product remains constant. The formula for inverse variation is \( y = \frac{k}{x} \), where \( k \) is a positive constant.

The relationship is non-linear and creates a hyperbolic shape when graphed. It showcases how two variables are inversely linked, affecting each other reciprocally. For instance, the speed of a car and the time it takes to reach a destination represent an inverse variation. The faster the car moves, the less time it takes to reach the destination.

Important points to remember about inverse variation include:
  • The product of the variables remains constant (\( xy = k \)).
  • Determine the inverse relation by finding \( k \).
  • Translate the scenario into an equation with the form \( y = \frac{k}{x} \).
Understanding these concepts helps to solve inverse variation problems effectively.
Constant of Variation
The constant of variation is a crucial component in both direct and inverse variation equations. It represents the fixed ratio or product in the relationship between variables.

In direct variation, the constant \( k \) represents how much one variable changes in relation to the change in another. If \( y \) varies directly with \( x \), expressed as \( y = kx \), then \( k \) stays consistent for all levels of \( x \) and \( y \).

In inverse variation, the constant \( k \) signifies the product of the two inversely varying variables. Here, \( y = \frac{k}{x} \) holds true, as long as \( k \) does not change, even though \( x \) and \( y \) do.

Key aspects of the constant of variation include:
  • Identifying what it represents in the equation.
  • Ensuring it remains unchanged within the given scenario.
  • Using it to solve for unknowns in the variation equation.
The constant of variation is pivotal, ensuring correct proportional changes in direct variation or consistent products in inverse variation.