Deriving the Specific Equation

Oct 13, 2025 by wbrum.org 91 views

Introduction

When working with physics equations, it's not uncommon to be given multiple equations and asked to derive a specific one. This can be a challenging task, especially if you're not familiar with the underlying concepts. In this article, we'll explore how to derive a specific equation based on two others, using the equations provided in a college physics textbook as an example.

The Given Equations

The two equations provided in the textbook are:

\qquad m_{1}v_{1i} + m_{2}v_{2i} = m_{1}v_{1f} + m_{2}v_{2f}\qquad \quad (9.15)

\qquad \qquad v_{1i} -v_{2i} = -(v_{1f} -v_{2f})\qquad \quad (9.16)

These equations describe the conservation of momentum in a two-object system. The subscripts "i" and "f" represent the initial and final states of the objects, respectively.

Deriving the Specific Equation

To derive the specific equation, we need to manipulate the given equations using algebraic techniques. Let's start by examining equation (9.16):

\qquad \qquad v_{1i} -v_{2i} = -(v_{1f} -v_{2f})

We can rewrite this equation as:

\qquad \qquad v_{1i} -v_{2i} = -v_{1f} + v_{2f}

Now, let's multiply both sides of the equation by $-1$ to get:

\qquad \qquad v_{2i} - v_{1i} = v_{1f} - v_{2f}

Using the First Equation to Derive the Specific Equation

Now that we have a modified version of equation (9.16), let's use equation (9.15) to derive the specific equation. We can start by rearranging equation (9.15) to isolate the term $m_{1}v_{1f}$ :

\qquad m_{1}v_{1f} = m_{1}v_{1i} + m_{2}v_{2i} - m_{2}v_{2f}

Now, let's substitute the expression for $m_{1}v_{1f}$ into the modified version of equation (9.16):

\qquad \qquad v_{2i} - v_{1i} = v_{1f} - v_{2f}

\qquad \qquad v_{2i} - v_{1i} = \frac{m_{1}v_{1i} + m_{2}v_{2i} - m_{2}v_{2f}}{m_{1}} - v_{2f}

Simplifying the Equation

Now that we have the specific equation, let's simplify it by combining like terms:

\qquad \qquad v_{2i} - v_{1i} = \frac{m_{1}v_{1i} + m_{2}v_{2i} - m_{2}v_{2f}}{m_{1}} - v_{2f}

\qquad \qquad v_{2i} - v_{1i} = \frac{m_{1}v_{1i} + m_{2}v_{2i}}{m_{1}} - \frac{m_{2}v_{2f}}{m_{1}} - v_{2f}

\qquad \qquad v_{2i} - v_{1i} = v_{1i} + \frac{m_{2}}{m_{1}}v_{2i} - \frac{m_{2}}{m_{1}}v_{2f} - v_{2f}

The Final Equation

After simplifying the equation, we get:

\qquad \qquad v_{2i} - v_{1i} = v_{1i} + \frac{m_{2}}{m_{1}}v_{2i} - \frac{m_{2}}{m_{1}}v_{2f} - v_{2f}

This is the specific equation we were asked to derive. It describes the relationship between the initial and final velocities of the two objects in the system.

Conclusion

Deriving a specific equation based on two others can be a challenging task, but it requires a deep understanding of the underlying concepts and algebraic techniques. By manipulating the given equations and using algebraic techniques, we can derive the specific equation and gain a deeper understanding of the physics behind the equations.

Key Takeaways

The specific equation describes the relationship between the initial and final velocities of the two objects in the system.
The equation can be derived by manipulating the given equations using algebraic techniques.
The specific equation is a fundamental concept in physics and is used to describe the behavior of objects in a two-object system.

Future Work

In the future, we can use this specific equation to derive other equations that describe the behavior of objects in a two-object system. We can also use this equation to solve problems that involve the conservation of momentum in a two-object system.

References

[1] Halliday, D., Resnick, R., & Walker, J. (2013). Fundamentals of Physics. John Wiley & Sons.
[2] Serway, R. A., & Jewett, J. W. (2018). Physics for Scientists and Engineers. Cengage Learning.

Note: The references provided are for example purposes only and may not be relevant to the specific topic being discussed.

Q: What is the purpose of deriving a specific equation based on two others?

A: The purpose of deriving a specific equation based on two others is to gain a deeper understanding of the physics behind the equations and to be able to solve problems that involve the conservation of momentum in a two-object system.

Q: How do I know which equation to derive?

A: The equation to derive is usually specified in the problem statement. In this case, we were asked to derive the specific equation that describes the relationship between the initial and final velocities of the two objects in the system.

Q: What are some common mistakes to avoid when deriving a specific equation?

A: Some common mistakes to avoid when deriving a specific equation include:

Not reading the problem statement carefully
Not understanding the underlying concepts
Not using algebraic techniques correctly
Not checking the units of the equation

Q: How do I check the units of the equation?

A: To check the units of the equation, you need to make sure that the units on both sides of the equation are the same. In this case, the units on both sides of the equation are velocity, which is measured in meters per second (m/s).

Q: What are some common applications of the specific equation?

A: The specific equation has many common applications in physics, including:

Solving problems that involve the conservation of momentum in a two-object system
Describing the behavior of objects in a two-object system
Understanding the relationship between the initial and final velocities of the two objects in the system

Q: How do I use the specific equation to solve problems?

A: To use the specific equation to solve problems, you need to:

Read the problem statement carefully
Understand the underlying concepts
Use algebraic techniques correctly
Check the units of the equation

Q: What are some common challenges when using the specific equation to solve problems?

A: Some common challenges when using the specific equation to solve problems include:

Not understanding the underlying concepts
Not using algebraic techniques correctly
Not checking the units of the equation
Not being able to apply the equation to a specific problem

Q: How do I overcome these challenges?

A: To overcome these challenges, you need to:

Read the problem statement carefully
Understand the underlying concepts
Use algebraic techniques correctly
Check the units of the equation
Practice applying the equation to different problems

Q: What are some resources that can help me learn more about deriving a specific equation based on two others?

A: Some resources that can help you learn more about deriving a specific equation based on two others include:

Textbooks on physics and mathematics
Online tutorials and videos
Practice problems and exercises
Online forums and communities

Q: How do I know if I have successfully derived the specific equation?

A: You can check if you have successfully derived the specific equation by:

Checking the units of the equation
Checking the algebraic techniques used
Checking the underlying concepts
Checking the problem statement

Q: What are some common mistakes to avoid when checking if you have successfully derived the specific equation?

A: Some common mistakes to avoid when checking if you have successfully derived the specific equation include:

Not checking the units of the equation
Not checking the algebraic techniques used
Not checking the underlying concepts
Not checking the problem statement

Conclusion

Deriving a specific equation based on two others can be a challenging task, but it requires a deep understanding of the underlying concepts and algebraic techniques. By following the steps outlined in this article and using the resources provided, you can successfully derive the specific equation and gain a deeper understanding of the physics behind the equations.