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### Momentum

Posted: Sun Oct 22, 2017 10:13 pm
If you are given the velocity and you are asked to find the kinetic energy, is there a constant that is used for the mass in kilograms? Does it change depending whether its a photon, electron, etc...?

### Re: Momentum  [ENDORSED]

Posted: Sun Oct 22, 2017 10:26 pm
I believe you would be given the mass also, typically the mass of a subatomic particle is given as kilograms in the DeBroglie equation

### Re: Momentum

Posted: Sun Oct 22, 2017 10:48 pm
The mass variable (m) will change according to what particle/object is given. I'd say typically the particle will be an electron, who's mass is 9.1093 x 10^(-31) kg, so you can use that. But the question should let you know what particle is being observed, and you would use that particle's mass for the m variable.

### Re: Momentum

Posted: Tue Oct 24, 2017 4:52 pm
Yea, it would be good to know the mass of an electron just as common chem knowledge, but I'm pretty sure he gave the mass of a proton, neutron and an electron on the last exam so you should generally be able to find the mass on the actual exam.