Comparing Velocities through Kinetic Energy

[Yousufshad]

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

 

[Ray Vickson]

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.

 

[Yousufshad]

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?

 

[SteamKing]

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?

 

[Yousufshad]

Have you studied algebra?

Sorry hadn't realized i made the mistake

3u^2=v^2
v = sqrt3 * u