Is This Equation Correct? p² = p₀² + 2mΔk

  • Thread starter Superstring
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It's also useful in situations where the mass is unknown or changing, so you can't use the simpler conservation of momentum equation.In summary, the conversation discusses the derivation of the equation p^2 = p_0^2 + 2mΔk, which is used to solve for the mass of an object based on its initial and final momentum and the change in its kinetic energy. This equation is useful in situations where the mass is unknown or changing.
  • #1
Superstring
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[tex]p^2=p_0^2+2m \Delta k[/tex]

I derived it using the following:

[tex]k=\frac{1}{2}mv^2[/tex]

[tex]p=mv[/tex]

[tex]\frac{dk}{dv}=mv=p[/tex]

[tex]\frac{dp}{dv}=m[/tex]

[tex]\frac{dk}{p}=dv[/tex]

[tex]\frac{dp}{m}=dv[/tex]

[tex]\frac{dk}{p}=\frac{dp}{m}[/tex]

[tex]mdk=pdp[/tex]

[tex]\int_{k_0}^{k}mdk=\int_{p_0}^{p}pdp[/tex]

[tex]m\Delta k=\frac{1}{2}(p^2-p_0^2)[/tex]

[tex]p^2=p_0^2+2m \Delta k[/tex]

As far as I can tell it's correct, but I though I'd get a second opinion.
 
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  • #2
Since p2 = 2mk, where k = ½mv2

mk = ½p2

m (k2 - k1) = ½(p22 - p12)

Bob S
 
  • #3
Isn't it easier to just note this?

[tex]\Delta k = k - k_0 = \frac{p^2}{2m} - \frac{p_0^2}{2m}[/tex]

Edit: Ninja'd.
 
  • #4
As well as what Bob S mentioned, I would say your equation is dimensionally valid.
By the way, why you need such an equation? Or what is it mainly used for?
 
  • #5
It's correct for speeds much smaller than that of light.
 
  • #6
Thanks for the responses :).

kiwakwok said:
By the way, why you need such an equation? Or what is it mainly used for?

As far as uses, it's a great deal simpler to solve for the mass than if you were to use a 3-equation system with p=mv, p0=mv0, and Δk=(m/2)(v2-v02) if you were only given p, p0 and Δk.
 

FAQ: Is This Equation Correct? p² = p₀² + 2mΔk

What is the process for checking the correctness of an equation?

The process for checking the correctness of an equation involves several steps. First, make sure that the equation is written in the correct format and follows the rules of mathematical notation. Then, check that all variables and constants are properly labeled and defined. Next, plug in sample values to test the equation and see if it produces the expected results. Finally, double check the equation for any potential errors or mistakes.

Can an equation be correct even if it doesn't have an equal sign?

Yes, an equation can still be correct even if it doesn't have an equal sign. In some cases, an equation may use an approximation symbol (∼) or a proportional symbol (∝) instead of an equal sign. These symbols still represent a relationship between two quantities and can be considered a correct equation if used appropriately.

How do you know if an equation is balanced?

An equation is considered balanced if both sides of the equal sign have the same number and type of terms. This means that the equation follows the law of conservation of mass and energy, where the total amount of matter or energy on one side is equal to the total amount on the other side. Additionally, the coefficients and exponents of each term should also be equal on both sides.

What are some common mistakes to look out for when checking the correctness of an equation?

Some common mistakes to look out for when checking the correctness of an equation include incorrect order of operations, missing or misplaced parentheses, incorrect use of variables, and incorrect use of mathematical operations. It is important to carefully review each step of the equation and double check for any potential errors or mistakes.

Can an equation be considered correct if it doesn't have units?

No, an equation cannot be considered completely correct if it does not have units. Units are an essential part of any mathematical equation as they provide context and meaning to the quantities being measured. Omitting units can lead to incorrect interpretations and calculations, so it is important to always include units in an equation to ensure its correctness.

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