## Kinetic Energy vs Power

$E=hv$

RichardValdez1L
Posts: 59
Joined: Fri Apr 06, 2018 11:05 am

### Kinetic Energy vs Power

Can 1/2mv^2 and mv be used for the same problem if we're only given kinetic energy or power? Like If we are given power, can we solve for kinetic energy?

Briana Lopez 4K
Posts: 44
Joined: Wed Nov 22, 2017 3:01 am

### Re: Kinetic Energy vs Power

The P in p=mv stands for momentum. The equation for Power is Force x Velocity. In a case where we are only given momentum, I think we can solve for Kinetic energy ( E=threshhold+KE ) if we substitute other equations for E and get it in terms of p=mv

E = threshold + KE
hv = threshold + KE
KE = hv - threshold ----> substituted Energy per photon equation (E=hv)
KE = h(c/λ) - threshhold ----> substituted Speed of Light equation ( nu=c/λ)
KE = h(c/(h/p)) - threshhold ----> substituted DeBroglie's equation (λ=h/p)
KE = hcp/h - threshhold
KE = cp - threshold -------> simplified
KE = c(mv) - threshhold ----> all that's left is the speed of light constant and momentum which is pretty good if we're only given p

I don't know if this is right or if it answers your question, but it makes sense to me right now haha

sameeksha_panda_3h
Posts: 31
Joined: Fri Sep 28, 2018 12:25 am

### Re: Kinetic Energy vs Power

Along with the previous response, I think to answer your question, you can solve if given power, but you'd also need to be given the force, or be able to solve for force with outside information. I'm not sure if we'd ever get a question like that or not though because that treads more into a physics question for a lot of it rather than just general chemistry.