# Homework Help: Calculate wavelength in pm associated with electron traveling 60% of the speed of lig

1. Nov 8, 2009

### Knight226

1. The problem statement, all variables and given/known data
Calculate the wavelength, in picometers, associated with an electron traveling 60.0% of the speed of light.

2. Relevant equations

Wavelength = h / (mv)

3. The attempt at a solution
I know the h value.
The v value I believe it is 60.0% of 3.00 x 10^8
But what is the m value? If the m value isn't given, then the equation can't be solved, can it?
Is there a specific number for the m value?

From the examples I have seem, the m for electrons are always different.

Last edited: Nov 8, 2009
2. Nov 10, 2009

### windwitch

Re: Calculate wavelength in pm associated with electron traveling 60% of the speed of

On the contrary, I am quite confident that the masses of electrons are always the same. It is the energy of electrons that changes.

The only time in which electrons may seem to have different masses in different questions are when an unfamiliar unit of measurement is used, or a different amount of significant figures is used. Nonetheless, the values should be relatively the same.

3. Nov 10, 2009

### Staff: Mentor

Re: Calculate wavelength in pm associated with electron traveling 60% of the speed of

What is the equation for mass increase as a function of velocity? How much does the mass increase at 0.6c?

4. Nov 11, 2009

### Staff: Mentor

Re: Calculate wavelength in pm associated with electron traveling 60% of the speed of

Google invariant mass and relativistic mass.

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