Determining Final Velocity of an Electron Absorbing an X-ray?

[gbaby370]

Hey, I was just wondering if someone could give me feedback on a problem. For some reason the answer is not in the back of the text.

Homework Statement

An x-ray with a wavelength of 2.5 x 10-8 m is absorbed by a stationary electron. Determine the final velocity of the electron.
Vxray=3.0x10^8 m/s
Velectron=0
melectron= 1.602x10^-19kg
mxray=(h/λc)
Velectron(after)=
h=6.626x10^-34Js
λ=2.5x10^-8

Homework Equations

Velectron(after)= Vxray((2(h/cλ))/(melectron+(h/cλ)))

The Attempt at a Solution

V(electronafter)= (3.0x10^8)((2((6.626x10^-34)/(3.0x10^8)(2.5x10^-8))/(1.602x10^-19)((6.626x10^-34)/(3.0x10^8)(2.5x10^-8)))

v(electronafter)= 3.31x10^-7m/s

Sorry if the formula is hard to understand, I used the formula for conservation of momentum in an elastic collision where one object is stationary before the collision.

 

[vela]

Your problem statement doesn't mention a proton. How does it come into the problem?

 

[gbaby370]

Sorry anywhere it says proton it should say electron.

 

[vela]

A solitary electron cannot absorb a photon. (Also if it did, it would be an inelastic collision, not an elastic collision.) If this problem is about the Compton effect, the photon scatters off the stationary electron.

Your value for the mass of the electron isn't correct.