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

$\lambda=\frac{h}{p}$

Mario Reyes 1C
Posts: 45
Joined: Fri Apr 06, 2018 11:04 am

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

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?

Elijah E 1C
Posts: 15
Joined: Fri Apr 06, 2018 11:02 am

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

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.

Mario Reyes 1C
Posts: 45
Joined: Fri Apr 06, 2018 11:04 am

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

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.

Jimmy lira-1G
Posts: 61
Joined: Fri Apr 06, 2018 11:03 am

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

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

JulietOttenberg-1C
Posts: 25
Joined: Fri Apr 06, 2018 11:04 am

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

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

Luis Torres 1C
Posts: 30
Joined: Fri Apr 06, 2018 11:05 am

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

Manipulating the DeBroglie wavelength equation can help with solving for velocity

$\lambda =\frac{h}{mass*velocity}$
$\lambda *mass*velocity=h$
$velocity=\frac{h}{\lambda *mass}$

Chem_Mod
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Joined: Thu Aug 04, 2011 1:53 pm
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### Re: How do you calculate speed using the De Broglie equation?

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