velocity and kinetic energy of a neutron


by carus88
Tags: quantum physics, x-ray tube
carus88
carus88 is offline
#1
Aug20-08, 05:54 PM
P: 14
Calculate the velocity and kinetic energy of a neutron (mass 1.675x10-27kg) that has a wavelength of 0.2nm. How does this compare to the average kinetic energy of a gas molecule at room temperature (0.038eV at 200C)?

1. E=mc^2

2. KE = 1/2 mv^2

I used 1. to calculate the energy which was 1.51 x10^-10 J

Then i subbed the energy into 2. and got a velocity of 4.24 x10^8 m/s

LOL obviously i'm going wrong some where how can a neutron be going faster than light!

CAN SOMEONE HELP PLEASE?
Phys.Org News Partner Science news on Phys.org
Internet co-creator Cerf debunks 'myth' that US runs it
Astronomical forensics uncover planetary disks in Hubble archive
Solar-powered two-seat Sunseeker airplane has progress report
will.c
will.c is offline
#2
Aug20-08, 07:13 PM
P: 374
First, the expression E=mc^2 does not give the kinetic energy of a particle. Second, even if it did, your method is immune to the given wavelength, so that should give you some idea where you should be looking.

How can you relate the wavelength of a particle to its momentum?
Dick
Dick is offline
#3
Aug20-08, 09:45 PM
Sci Advisor
HW Helper
Thanks
P: 25,178
This is the same as http://www.physicsforums.com/showthread.php?t=251160 carus88, don't multiple post.


Register to reply

Related Discussions
[SOLVED] Kinetic Energy and Velocity Introductory Physics Homework 10
An UHECR neutron (kinetic energy 10^19 eV) approaches a magnetar (B = 10^10 T) High Energy, Nuclear, Particle Physics 6
Kinetic Energy and Velocity Introductory Physics Homework 2
Trying to find Velocity and Kinetic Energy! Introductory Physics Homework 3
Velocity w/ kinetic energy Introductory Physics Homework 15