IB Physics Topic 1: Physics and Physical Measurement. Note: annotations for the 2016 curriculum have been added to this video but may not appear on some devices.
Fantastic video and explanations! I have a question - you had a comment box that popped up at the end about the max and min slopes and how they have to consider every error box, but the max gradient didn't go through most boxes. Also, aren't there many gradients that one can draw in between the max and the min? Or should we always use LoggerPro? Thanks!
Also, on your measurement of digital voltmeter, I would have liked you to mention what to do when there are lower end figures fluctuating. Some sensitive devices fluctuates at the lower ends a lot. Also the source you are measuring can itself be fluctuating very slightly. So it is necessary to cut off the lower ends of the values and decide how many significant figures are reliable reading.
What you are referring to is an experimental issue. In the academic sense, meters do not fluctuate. As I mentioned in the video these are best case conditions. If you observe anything in your experiment that adds to uncertainty you need to note it and assign additional uncertainty based on your qualitative observations.
Keep going with the amazing work. Really helpful. However sometimes, I don't know where the next or the previous video is. If you write the links of all the videos of the subject in the description, it could help. Sorry for the bad english.
Brian, if I'm getting the area of a rectangle and area and I have .6 uncertainty in the area what I do with the uncertainties, do I sum them or multiply them? Great video btw saving my physics semester
So for the analog measurements the 0.5 uncertainty ,etc (depends on the number of sigfig) is always constant? Then for the digital, it will always be 0.1, etc... correct me if I’m wrong 😭
I would like to ask a question on your take on the analog voltmeter reading. I would quote the reading as 22.5 plus or minus 0.5V. The needle has definitely passed the 22V mark and it seems to be between the 22V and 23V marks. Am I wrong?
It's difficult to see, but when I use a magnifying lens I can also see the needle is between 22 and 23. So upon closer inspection I would agree with you .
Brian Lamore Hallo, thank you for making this great video! It has helped me a lot. However, it says in this year's IB Physics book that the maximum and minimum trend lines have to pass through all of the error bars. Has this then been changed from last year's syllabus?
Hey so when doing an experiment that involves measuring using a metre rule will you record the measurement( uncertainty) as say 13+/- 0.1 cm or 13+/-0.05cm, I will be so greatful if you answer me Sir
Most analog metre rules have a resolution of 0.1cm. Half this is 0.05cm. If you are using the rule such that there is uncertainty at *both* ends, the total uncertainty is 0.1cm.
Hi, not sure if you still check this video, if you do please could you explain why at 4:24, that the digital uncertainty is ±0.01V? I don't understand why it would not be ±0.005V, since if the value in the example was 19.16V ±0.01V, this would mean that upper bound would be 19.17 and the lower bound would be 19.15, which, according to the uncertainty of ±0.01V, would result in 19.16V being recorded, when in reality they would not? Thanks.
The uncertainty is +/-0.01V, because the digital meter displays to the hundredths place. Whatever the last decimal place shown is, put a 1 there, and that is the uncertainty.
Great video... quick question. What is your suggestion when measuring different types of measurements? For example, temperature (in Celsius) + salinity (in parts/thousand) + depth (meters). Essentially, these 3 measurement types allow to calculate speed of sound in sea water (see resource.npl.co.uk/acoustics/techguides/soundseawater/content.html#UNESCO). Thanks for any feedback on this question.
In IB Physics we combine uncertainty from mult/div by simply adding the relative uncertainties. E.g., if there is a 10% uncertainty in both A and B, they A*B and A/B would have an uncertainty of 20%. The RSE would be only 14%. The IB-way may be worst case, but I think the IB-way is meant to be easier yet still allow the students to appreciate uncertainty.
+Brian Lamore ah true, I guess you just wanted to round up to the same number of decimal places as in the number to which the uncertainty is connected, now everything seems just fine.
for the uncertainties, do we round them early in the calculation or after all calculations? if i get a long decimal value for the uncertainty , do i round it or continue with the calculation until after i added all the uncertainties?
Im quite confused bcs other videos would tell that uncertainty of measurement would be equal to the resolution or the least count, can u somehow explain it sir? Thnks
When it comes to ruler or other measurements uncertainty should equal to resolution but with readings such as glass instruments they would say its half of the resolution. Can u clarify it sir?
If we are going to follow the rule of the digital devices "+or - smallest unit shown" that means for uncertainty for digital devices always going to be .01, .001, .1 is that right?
I am in my second week at uni, and I've discovered that all of the pretty much all the uncertainty propagation formulas we are taught in IB are FALSE. So learn them well for the exam, but forget about it after the exams
That's probably true. IB never claimed theirs is the best way to determine uncertainties; their objective is to get the student to 1) appreciate uncertainty and 2) understand that they propagate through calculated quantities.
This is not the way you find the propagation of errors of a calculated quantity such as the area of a box you did it. Please review this link from Harvard University ipl.physics.harvard.edu/wp-uploads/2013/03/PS3_Error_Propagation_sp13.pdf
What I presented here was the method IB required. IB is aware there are other methods, but their purpose was to get the student to appreciate uncertainty and propagation. You are welcome to contact IB.
@@bclamore Thank you for your reply! What is IB? If you are doing the volume of a cylinder, the radius has power of 2 and height power of 1. So the uncertainty of the radius in the volume is bigger than that of height. Based on your formula they both will have the same weight in the volume uncertainty.
This video made me completely prepared for the upcoming test on Uncertainties. Thank you for explaining it so clearly.
I never understood errors in physics until I saw this.
Thank you so much, so helpful. You make it so easy to understand.
Fantastic video and explanations! I have a question - you had a comment box that popped up at the end about the max and min slopes and how they have to consider every error box, but the max gradient didn't go through most boxes. Also, aren't there many gradients that one can draw in between the max and the min? Or should we always use LoggerPro?
Thanks!
I was very confused in class but this explains a lot, thank you.
Thanks for this amazing video. I just watched it for my exam. It helped a lot.
You are a life savior. Thanks a million!!!
Will you be doing newer videos for the new Physics HL?
Excellent video to understand the basic concepts.
in 5:39 the average value should be 1561.6 instead of 1563 so would we round the average to 1562 or do we leave it like that?
Bryan Perera he added that highest number and the least number, then divide it by 2. Answer is 1562.5, round it up, so the answer will be 1563.
Shane Gepilano no he's your right bryan it should be rounded up to 1562
Also, on your measurement of digital voltmeter, I would have liked you to mention what to do when there are lower end figures fluctuating. Some sensitive devices fluctuates at the lower ends a lot. Also the source you are measuring can itself be fluctuating very slightly. So it is necessary to cut off the lower ends of the values and decide how many significant figures are reliable reading.
What you are referring to is an experimental issue. In the academic sense, meters do not fluctuate. As I mentioned in the video these are best case conditions. If you observe anything in your experiment that adds to uncertainty you need to note it and assign additional uncertainty based on your qualitative observations.
You're an amazing teacher. Thanks for making this video.
Keep going with the amazing work. Really helpful. However sometimes, I don't know where the next or the previous video is. If you write the links of all the videos of the subject in the description, it could help. Sorry for the bad english.
Watch the Playlist -- the videos are in order there.
Thank you:)) My evaluative assessment on Monday. You helped me a lot:))
really nice video
Brian, if I'm getting the area of a rectangle and area and I have .6 uncertainty in the area what I do with the uncertainties, do I sum them or multiply them? Great video btw saving my physics semester
gabriel lozano The uncertainty in the area depends on the uncertainty of the length and width. I'm not sure what you are asking.
i am doing year 11 physics and this really helped to do one of my assessment
Really Helpful!
YOU ARE GOD
Thank you for this! Super helpful for A Level exam prep :D
Saved my life! ;)
So for the analog measurements the 0.5 uncertainty ,etc (depends on the number of sigfig) is always constant? Then for the digital, it will always be 0.1, etc... correct me if I’m wrong 😭
I would like to ask a question on your take on the analog voltmeter reading. I would quote the reading as 22.5 plus or minus 0.5V. The needle has definitely passed the 22V mark and it seems to be between the 22V and 23V marks. Am I wrong?
It's difficult to see, but when I use a magnifying lens I can also see the needle is between 22 and 23. So upon closer inspection I would agree with you .
Great video, but shouldn't your maximum and minimum gradients fall within all the error bars?
Brian Lamore Hallo, thank you for making this great video! It has helped me a lot. However, it says in this year's IB Physics book that the maximum and minimum trend lines have to pass through all of the error bars. Has this then been changed from last year's syllabus?
Maria Skjeltorp Yes, you are correct. I have added annotations to help avoid confusion. Thank you!
one of the best presentation
Thank you sir for your nice and really helpful lecture.
What about for time measurements? How do you find their absolute uncertainty?
Yea but the average at 6:00 is actually 1561.6 mm and not 1563mm.
what is the difference between root-squared error(maximum error) and combining uncertainties of multiplication/division?
Hey so when doing an experiment that involves measuring using a metre rule will you record the measurement( uncertainty) as say 13+/- 0.1 cm or 13+/-0.05cm, I will be so greatful if you answer me Sir
Most analog metre rules have a resolution of 0.1cm. Half this is 0.05cm. If you are using the rule such that there is uncertainty at *both* ends, the total uncertainty is 0.1cm.
Hi, not sure if you still check this video, if you do please could you explain why at 4:24, that the digital uncertainty is ±0.01V? I don't understand why it would not be ±0.005V, since if the value in the example was 19.16V ±0.01V, this would mean that upper bound would be 19.17 and the lower bound would be 19.15, which, according to the uncertainty of ±0.01V, would result in 19.16V being recorded, when in reality they would not?
Thanks.
The uncertainty is +/-0.01V, because the digital meter displays to the hundredths place. Whatever the last decimal place shown is, put a 1 there, and that is the uncertainty.
Okay thank you very much
Thank u so much man
Great video... quick question. What is your suggestion when measuring different types of measurements? For example, temperature (in Celsius) + salinity (in parts/thousand) + depth (meters). Essentially, these 3 measurement types allow to calculate speed of sound in sea water (see resource.npl.co.uk/acoustics/techguides/soundseawater/content.html#UNESCO).
Thanks for any feedback on this question.
Depends on how terms are combined. If the terms are multiplied, then find the relative (percent) uncertainty in each term and add those percentages.
Thank you sir for your video can you give some questions on this chapter too
In IB Physics we combine uncertainty from mult/div by simply adding the relative uncertainties. E.g., if there is a 10% uncertainty in both A and B, they A*B and A/B would have an uncertainty of 20%. The RSE would be only 14%. The IB-way may be worst case, but I think the IB-way is meant to be easier yet still allow the students to appreciate uncertainty.
3:44 I would read this as 22.5 ± 0.1V .
7:26 shouldn't the uncertainity be 0.5 cm as you take half of the scaling? or is it just a value rounded up to 1s.f.?
+gutttab I chose an arbitrary value (+/-1cm) to illustrate the point about accuracy vs. precision. (BTW, 0.5cm and 1cm both have 1 s.f.)
+Brian Lamore ah true, I guess you just wanted to round up to the same number of decimal places as in the number to which the uncertainty is connected, now everything seems just fine.
for the uncertainties, do we round them early in the calculation or after all calculations? if i get a long decimal value for the uncertainty , do i round it or continue with the calculation until after i added all the uncertainties?
Joe keep all your decimal places until the final answer😃
great video, cheers.
Im quite confused bcs other videos would tell that uncertainty of measurement would be equal to the resolution or the least count, can u somehow explain it sir? Thnks
When it comes to ruler or other measurements uncertainty should equal to resolution but with readings such as glass instruments they would say its half of the resolution. Can u clarify it sir?
Digital instruments use the least count as a measure of uncertainty. Analog instruments (like ruler or glass) use half the smallest gradation.
Thank you! This was helpful.
If we are going to follow the rule of the digital devices "+or - smallest unit shown" that means for uncertainty for digital devices always going to be .01, .001, .1 is that right?
Yes.
Ok, thank u
Great video!
Thanks,, well explained!
Very good.
thanks
I am in my second week at uni, and I've discovered that all of the pretty much all the uncertainty propagation formulas we are taught in IB are FALSE. So learn them well for the exam, but forget about it after the exams
That's probably true. IB never claimed theirs is the best way to determine uncertainties; their objective is to get the student to 1) appreciate uncertainty and 2) understand that they propagate through calculated quantities.
Omds you're amazing
is a thermometer a a analog d evice?
well if its not digital then of course.
very helpful, thx
clear explanation
I'm not understanding why at 05:51 the +/- is 5mm... Can anyone help?
4.5mm is rounded up to 5mm. Uncertainty has 1 sig fig. Or it used to... I am not teaching this anymore, and IB may have changed their curriculum.
@@bclamore ah yes, I understand now. Thank you
nice video man
06/06/2024
15:02
This is not the way you find the propagation of errors of a calculated quantity such as the area of a box you did it. Please review this link from Harvard University ipl.physics.harvard.edu/wp-uploads/2013/03/PS3_Error_Propagation_sp13.pdf
What I presented here was the method IB required. IB is aware there are other methods, but their purpose was to get the student to appreciate uncertainty and propagation. You are welcome to contact IB.
@@bclamore Thank you for your reply! What is IB?
If you are doing the volume of a cylinder, the radius has power of 2 and height power of 1. So the uncertainty of the radius in the volume is bigger than that of height. Based on your formula they both will have the same weight in the volume uncertainty.
Kafam iyice karışıyor
hello
really helpful really boring though
plz to explain clearly....nice not a good