Question

What is the speed of a 50 g rock if its de broglie wavelength is 3.32x10^-34m?

Answer 1

We can find the momentum of the rock by using De Broglie's relationship:

`p= (h)/(\lambda)`
where
p is the momentum
h is the Planck constant

`\lambda` is the De Broglie's wavelength

By using
`\lambda=3.32 \cdot 10^(-34) m`, we find

`p= (6.6 \cdot 10^(-34) Js)/(3.32 \cdot 10^(-34) m)=1.99 kg m/s`

The momentum of the rock is

`p=mv`
where
`m=50 g=0.05 kg` is the mass and v is its velocity. Rearranging the equation, we find the speed of the rock:

`v= (p)/(m)= (1.99 kg m/s)/(0.05 kg)=39.8 m/s`