Calculate Smallest Distance Between Baby Parts with Ultrasound Pulses

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Homework Help Overview

The discussion revolves around calculating the smallest distance between parts of a baby as detected by ultrasound pulses, specifically focusing on the timing and separation of reflections from these pulses. The subject area includes concepts from wave physics and ultrasound technology.

Discussion Character

  • Exploratory, Conceptual clarification, Problem interpretation

Approaches and Questions Raised

  • Participants explore the relationship between the duration of ultrasound pulses and the distance that can be resolved between two reflections. There are attempts to use analogies, such as comparing the situation to trucks turning around, to clarify the concept. Questions about the correct symbol for micro and the underlying theory are also raised.

Discussion Status

Some participants have provided analogies and interpretations to help clarify the problem. There is an ongoing exploration of how to calculate the length of the pulse based on speed and time, with some guidance offered on the relationship between distance and pulse length. However, there is no explicit consensus on the final calculations or outcomes.

Contextual Notes

Participants are working within the constraints of a homework assignment, which may limit the depth of explanation and the completeness of the solutions discussed. There are also questions regarding the correct use of symbols and terminology in the context of the problem.

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Homework Statement



If the ultrasound pulses are 3.5 microseconds (is \mu the right symbol for "micro"?) long, and travel 100mm in 70 micro seconds, what is the smallest distance one part of a baby can be behind another if the reflections can just be told apart (dont get mixed together in time).

Homework Equations



v = f x wavelength maybe?

The Attempt at a Solution



I couldn't find out how to do it in the textbook

can someone please explain the theory behind it, and possibly leave the calculation to me?

thnx
 
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I'll give an analogy which I think will help illustrate what's happening... suppose you have 2 trucks each of length L... they are driving side by side at the same speed. At some point the first truck turns around in the opposite direction... the second truck turns around at a distance X beyond the spot where the first truck turned around...

How long does the distance X have to be, so that no parts of the two trucks are side by side... meaning one truck is completely behind the other on the way back?
 
Last edited:
umm, 0.5L by any chance?

cant really work it out mathematically, but that's what it would seem right logically in my head. because as one of the trucks turns around, by the time one of the truck goes distance 0.5L to X the one that has turned around has gone back 0.5L right?
 
Trail_Builder said:
umm, 0.5L by any chance?

cant really work it out mathematically, but that's what it would seem right logically in my head. because as one of the trucks turns around, by the time one of the truck goes distance 0.5L to X the one that has turned around has gone back 0.5L right?

Yes, exactly right. Thinking of the pulses like trucks that turn around in the same way... the distance between the two parts of the baby has to be 0.5*length of the pulse. Can you calculate the length of the pulse?

Find the speed of the pulse first. Then you can get the length.
 
Last edited:
so speed would be 0.1/0.00007 m/s

distance = speed x time, so i take it the length of the pulse is 0.005, and the so the final answer will be 0.0025m?

thnx for the help buddy

...

just check the answers and I am right :D

thnx
 
Trail_Builder said:
so speed would be 0.1/0.00007 m/s

distance = speed x time, so i take it the length of the pulse is 0.005, and the so the final answer will be 0.0025m?

thnx for the help buddy

...

just check the answers and I am right :D

thnx

Cool! Good job! :smile:
 

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