Comparing Velocities through Kinetic Energy

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Homework Help Overview

The discussion revolves around a problem in kinetic energy involving an oxygen atom and a helium atom, where the oxygen atom is three times more massive than the helium atom. Both atoms are stated to have the same kinetic energy, and the goal is to find the ratio of their velocities.

Discussion Character

  • Exploratory, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss the kinetic energy equations for both atoms and attempt to isolate variables to find the velocity ratio. There is confusion regarding the cancellation of terms and the need to denote different variables for the velocities of the two atoms.

Discussion Status

Participants are actively engaging with the problem, with some providing algebraic manipulations and others questioning assumptions. There is acknowledgment of mistakes and a progression towards clarifying the relationship between the velocities.

Contextual Notes

There is a mention of needing to denote different velocities for the two atoms, indicating a potential misunderstanding of the problem setup. The discussion reflects an exploration of algebraic relationships without resolving the final ratio.

Yousufshad
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Homework Statement


An oxygen atom is 3.00 times as massive as a helium atom. In an experiment, a helium atom and an oxygen atom have the same kinetic energy. What is the ratio VHe/VO?

Homework Equations


KE = 1/2 mv^2

The Attempt at a Solution


I know KE for helium is = 1/2 mv^2
and KE for Oxygen is = 1/2 3mv^2

and KE are the same so

1/2 mv^2 = 1/2 3mv^2

Now I am having trouble isolating and solving for v, they seem to just cancel out
 
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Yousufshad said:

Homework Statement


An oxygen atom is 3.00 times as massive as a helium atom. In an experiment, a helium atom and an oxygen atom have the same kinetic energy. What is the ratio VHe/VO?

Homework Equations


KE = 1/2 mv^2

The Attempt at a Solution


I know KE for helium is = 1/2 mv^2
and KE for Oxygen is = 1/2 3mv^2

and KE are the same so

1/2 mv^2 = 1/2 3mv^2

Now I am having trouble isolating and solving for v, they seem to just cancel out

You have two different atoms, so need two different v's.
 
Ray Vickson said:
You have two different atoms, so need two different v's.

1/2 mv^2 = 1/2 3mu^2

Ok denoting them differently u = sqrt(1/3 mv^2) how do i get a ratio of v/u?
 
Yousufshad said:
1/2 mv^2 = 1/2 3mu^2

Ok denoting them differently u = sqrt(1/3 mv^2) how do i get a ratio of v/u?
Have you studied algebra?
 
SteamKing said:
Have you studied algebra?

Sorry hadn't realized i made the mistake

3u^2=v^2
v = sqrt3 * u
 

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