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### How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 10:24 pm**

by **Mario Reyes 1C**

I do not understand how to calculate speed using the De Broglie equation? Is it the same as calculating the velocity? If so, how do you calculate the velocity?

### Re: How do you calculate speed using the De Broglie equation? [ENDORSED]

Posted: **Sun Apr 22, 2018 10:32 pm**

by **Elijah E 1C**

Speed would be the same as velocity. Since the De Broglie equation is wavelength=Planck's constant/momentum and we know momentum is mass times velocity you can rearrange the equation to find velocity.

### Re: How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 10:47 pm**

by **Mario Reyes 1C**

So rearranged, the equation for velocity would be plancks constant / (wavelength)(mass) correct? I used this equation for #34 solving for speed and did not get the correct answer, which was the reason I was unsure if speed and velocity were the same.

### Re: How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 10:48 pm**

by **Jimmy lira-1G**

Just to clarify,

wavelength= h / m

h= plancks constant 6.626 x 10^-34 j s

m= momentum= velocity x mass

so

m= h/ wavelength

velocity= h/ wavelength / mass

- Jimmy lira 1g

### Re: How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 10:53 pm**

by **JulietOttenberg-1C**

yes velocity is (planck's constant)/(wavelength)(mass). I'm fairly certain the main difference between velocity and speed is direction, and I think the only possible thing that could change in your answer is the positive or negative sign. Maybe check the numbers and there might be a miscalculation

### Re: How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 11:03 pm**

by **Luis Torres 1C**

### Re: How do you calculate speed using the De Broglie equation?

Posted: **Sun Apr 22, 2018 11:05 pm**

by **Chem_Mod**

Another note: velocity is a vector and speed is the magnitude of that velocity vector since it does not indicate direction.