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# quantum mechanics watch

1. how do you find the minimum velocity an object of mass m, has to travel to be diffracted through a slit of length d?
2. Use DeBroglies formula with p=mv.
3. Isn't this physics, not maths?

Anyway yeah using λ = h/(m.v).

Combine it with diffraction formula, substituting to cancel out λ:

λ = dsinθ

Where θ is the angle of diffraction.

Which would give:

dsinθ = h/(m.v)

v = h/(m.d.sinθ )

Not to sure how you'd go about finding some sort of minimum velocity. I guess you would say the angle is 90° maybe?
4. at sinθ = 90° (that's what i did)

λ = d

lets say d is 1meter

m is 1kg

then, v = h/mλ
therefore, v = h/m, which seems pretty slow to me
5. h is something like but m is about and d is typically or something like that.

You can't put in d=1, m=1 and expect a sensible answer. h is a quantum constant, so you have to put in quantum sized lengths to expect a sensible answer.
6. hmm, the question was "what's the velocity a person has to walk to go diffract through a doorway"
7. Then you're supposed to get a silly answer. And in case anyone's worried, walking slowly through a doorway won't diffract you all over the walls It's just a negligibly small possibility...
8. haha right, thanks then

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