Find Velocity of Electron: Combining Equations

[Narv]

I need to find the velocity of an electron, and the information i have is the Electrical Charge, Mass and voltage difference. The math itself won't be the problem, but combining the two equations below to give the third is driving me nuts.

I need someone to explain how Ek (kinetic energy) could equal ΔEe (change in electrical energy) so they can be combined, or if I am totaly wrong, a point in the right direction:

Ek = ½ mv²

ΔEe = QΔV

To give:

v = √2QΔV/m

I was provided the final equation by a friend as a hint, and the only two equations i can find with relevant values are the two above, so I think I'm along the right track. Its just the reason WHY they can be combined that's confusing me.

Thank you.

 

[rock.freak667]

By conservation of energy, the pd used to speed up the electron is converted into KE.

hence QΔV=½ mv²

 

[Narv]

By conservation of energy, the pd used to speed up the electron is converted into KE.

hence QΔV=½ mv²

You, Sir, are a wonderful human being, and will have the finest of riches, the most beautiful of women and the highest prestige when I accomplish world domination.

I also owe you a beer.

Thank you very much :)

 

[rock.freak667]

You, Sir, are a wonderful human being, and will have the finest of riches, the most beautiful of women and the highest prestige when I accomplish world domination.

I've never heard that one before!