How Precisely Can the Position of a Flying Mosquito Be Known?

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SUMMARY

The discussion focuses on calculating the uncertainty in the position of a mosquito with a mass of 0.15 mg flying at a speed of 50 cm/s, with a velocity uncertainty of ±0.5 mm/s. The key equation used is the Heisenberg Uncertainty Principle, represented as Δp * Δx = ħ / 2, where Δp is the uncertainty in momentum. The correct approach involves calculating Δp using the mass and the uncertainty in velocity, leading to the determination of the uncertainty in position (Δx).

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zoner7
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Homework Statement


A mosquito of mass .15mg is found to be flying at a speed of 50 cm/s within an uncertainly of .5 mm/s.

a) How precisely can it's position be known?


Homework Equations



Delta p * Delta x = h bar / 2
p = mv

The Attempt at a Solution



I look at problem originally and simply solved for momentum using the given velocity 50 cm/s. Then i plugged that into the delta x * delta p = h bar / 2.
I got the answer 7.033 X 10^-31

Then I realized that I never used the variable describing the uncertainly of the fly's velocity. Clearly this is relevant to the solution of the problem. I think that I calculated the acutal momentum, as opposed to the uncertaintly of momentum, which the above equation calls for. How am I supposed to differentiate between the actual velocity and the uncertaintly of velocity?

Does the problem want me to give a range of positions? I could solve for the uncertainly of momentum using 50 cm/s + or - .5 mm/s. Could I then could find a max and a min position using the uncertainly equation? What exactly should I be solving for?

Thank you in advance!
 
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zoner7 said:
I look at problem originally and simply solved for momentum using the given velocity 50 cm/s. Then i plugged that into the delta x * delta p = h bar / 2.

You found momentum p, which is not what the equation uses. It uses delta p.

Given that [itex]p=mv[/itex] , then [itex]\Delta p=m\Delta v[/itex].

The problem just wants to know delta x.
 
Last edited:

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