Exercise 1.45


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Kellina Tran 2I
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Joined: Sat Jul 22, 2017 3:00 am

Exercise 1.45

Postby Kellina Tran 2I » Wed Oct 25, 2017 7:18 pm

For exercise 45 of chapter 1 regarding the Heisenberg Indeterminacy, the problem tells us that the bowling ball is rolled at 5.00 +/- 5.0 m.s^-1. What does the +/- part tell us and what do we do with that in our work? I noticed that the solutions manual only uses 5.0 m/s^-1, so I am not sure where the +/1 comes in.

Jessica Jones 2B
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Re: Exercise 1.45

Postby Jessica Jones 2B » Wed Oct 25, 2017 8:39 pm

The +/- is the indeterminacy of the velocity. You add both the +5 and -5(but keep it positive for the addition) together and your indeterminacy of velocity variable is equal to 10 an you would substitute this in for the variable.

Angelica Mercado 1A
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Re: Exercise 1.45

Postby Angelica Mercado 1A » Sun Oct 29, 2017 3:38 pm

The +/- part indicates a range of uncertainty, which is why you get the absolute value of +5 and -5 to get the indeterminacy of velocity variable, 10. But I'm also wondering why the solutions manual doesn't subsitute delta v with 10, rather than just 5m/s^-1?

Elika Asis 3C
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Re: Exercise 1.45

Postby Elika Asis 3C » Mon Oct 30, 2017 12:42 am

The +/- indicates that theres a range of indeterminacy in where the velocity of an electron (or whatever molecule there is) because once a photon or source of energy hits the electron, the momentum of both are much more similar than to what a photon would have to a baseball would have, and the direction/path/position of the electron gets disturbed, so we don't know the exact distance the electron has travelled. Hope that helps!

MichelleTran3I
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Re: Exercise 1.45

Postby MichelleTran3I » Mon Oct 30, 2017 5:07 pm

This does not answer your question regarding the +/- but the solutions manual states 5.0 m/s-1 as delta v, but delta v should actually be 10 m/s-1. It is simply an error and can be found in the Solutions Manual Errors link on the class website. It should clear up any confusion when it comes to determining the the final answer based on the given information.


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