# Using a spirometer to calculate breathing rate

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Thread starter 2 years ago
#1
Here's a link to the question Q4
https://pmt.physicsandmathstutor.com...%20A-level.pdf

Here's a link to the mark scheme:
https://pmt.physicsandmathstutor.com...%20A-level.pdf

What do they mean calibrate volume and time? How ?
Last edited by Leah.J; 2 years ago
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2 years ago
#2
The spirometer can be calibrated for volume by syringing a known volume through it.

As the diagram shows a kymograph being used to record the trace, time calibration depends on its rotation speed.
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Thread starter 2 years ago
#3
(Original post by Old_Microbials)
The spirometer can be calibrated for volume by syringing a known volume through it.

As the diagram shows a kymograph being used to record the trace, time calibration depends on its rotation speed.
Right.. um, so what should I say for the time calibration point ? Calibrate the time by setting a specific rotation speed ?
I'm sorry I self study bio and I'm a bit confused about this
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2 years ago
#4
Well, if you want to know the breaths per second for example, you need to be able to ascertain what a second looks like on the graph.
If the rate of rotation was 1 mm per second, then each mm of trace would represent 1 second.
So breaths per minute would be the number of breaths over a 60mm trace.

(Original post by Leah.J)
Right.. um, so what should I say for the time calibration point ? Calibrate the time by setting a specific rotation speed ?
I'm sorry I self study bio and I'm a bit confused about this
1
Thread starter 2 years ago
#5
(Original post by Old_Microbials)
Well, if you want to know the breaths per second for example, you need to be able to ascertain what a second looks like on the graph.
If the rate of rotation was 1 mm per second, then each mm of trace would represent 1 second.
So breaths per minute would be the number of breaths over a 60mm trace.
Ohhhh, I got it, thank you!
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