Impossible heisburg uncertainty question that makes no sense

AI Thread Summary
The discussion revolves around calculating the minimum uncertainty in the speed of a quantum-mechanical duck named Fuzzy, given its mass and position constraints. Participants express confusion over the application of the uncertainty principle, particularly in deriving the correct values for speed and position uncertainties. One user attempts to solve the problem but arrives at an incorrect value of 8.88, prompting a critique of their calculations and assumptions regarding velocity and speed. The conversation highlights the nuances of interpreting quantum mechanics equations, especially the distinction between speed and velocity uncertainties. Ultimately, the correct approach emphasizes the need for precise calculations and understanding of the principles involved.
footballfreak
Messages
6
Reaction score
0

Homework Statement



Suppose Fuzzy, a quantum-mechanical duck, lives in a world in which h = 2πJ · s. Fuzzy has a mass of 1.80 kg and is initially known to be within a pond 1.00 m wide. (a) What is the minimum uncertainty in the duck's speed?
1(b) Assuming this uncertainty in speed to prevail for 5.40 s, determine the uncertainty in Fuzzy's position after this time.

Homework Equations


xp=h/4(3.14)


The Attempt at a Solution


tried it a million different ways
 
Physics news on Phys.org
Well can you tell us what you tried, and tell us the right answer that you are failing to get?
 
im doing online homework
 
(a) I plugged all the numbers into the equation using 2pie for h and I get 8.88 and its off by orders of magnitude (b) I have no idea
 
How did you get 8.88?
if delta x * m * delta v = h/4 = 2pi / 4 = pi / 2
then
delta v = Pi / (2 * 1 m * 1.8 kg) = Pi Js / 3.6kgm
pi/3.6 is NOT 8.88 ... it's going to be a little less than 1

and that's not even considering the fact that the uncertainty in speed should be half of the uncertainty of velocity (though I've even seen some textbooks that don't even consider the fact that velocity can be in both directions, and take the uncertainty in velocity to be the uncertainty in speed...however, the book that i learned quantum mechanics from had the uncertainty in speed as half the uncertainty in velocity for all the questions ...i don't know how your online service works, but if 8.88 is off by EXACTLY an order of magnitude, then the real answer would be 0.87 and not half of that)
 
Last edited:
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...
Back
Top