Thank you for the video. Why do you have d=0.449+-0.010 and not just d=0.45+-0.01. with measuremnt accuracy 0.01 the third digit does not matter. In the same way you can write d=0.4482+-0.0100 and so on. I can be totally wrong here. If we have 1, we might need to use one more digit... Thank you!
This is a quirk of how we record uncertainties, particularly in A-Level Physics. We give uncertainties to two significant figures in A-Level Physics, so the zero after the 0.01 is significant. Then we match the decimal places for the mean value (0.449 rather than 0.45). Taking repeats should improve accuracy, but the way we calculate uncertainties in A-Level Physics is a bit too simplistic. Still, it gets students thinking about them, which is enough for now.
im second year engineering in uni not believing this is a-level. oh the curse of doing an access course! gaahhhh. great video tho thanks! I know all this gubbins through theory only!
Sincerely, it is A-Level. This is a required practical on the current syllabus, so all A-Level Physics students must do it and are assessed against five 'competencies' (the Common Practical Assessment Criteria, or CPAC). In the video, I actually fall short of the requirement for Competency 3, working safely in a laboratory 🤦♂️ but I'm not going to do it all again.
Subtracting the zero error is correct. It's a negative value, so subtracting a negative value increases the measurement. Each measurement was 0.01mm too small, so subtracting negative 0.01mm is the correct approach.
@@PhysicswithKeith If I go to the gym, and would like to measure my weight. Then I see a scale, but before I get on the scale, it reads 5kg. When I got on it, it reads 70kg. I will see the 5kg as a positive error, and my real weight is 70-5=65kg. Please enlighten me Prof what my weight would be if the scale was reading a negative error of -5kg before I get on it.
@@eagle43257 if the zero error on the balance is +5kg, you subtract +5kg from the mass measurement. If the zero error on the balance is -5kg, you subtract -5kg. If your mass is 65kg, then a +5kg zero error would cause the measurement to be 70kg. 70kg subtract positive 5kg is 65kg. If your mass is 65kg, then a -5kg zero error would cause the measurement to be 60kg. 60kg subtract negative 5kg is 65kg. You always subtract the zero error.
Thank you for the video. Why do you have d=0.449+-0.010 and not just d=0.45+-0.01. with measuremnt accuracy 0.01 the third digit does not matter. In the same way you can write d=0.4482+-0.0100 and so on. I can be totally wrong here. If we have 1, we might need to use one more digit... Thank you!
This is a quirk of how we record uncertainties, particularly in A-Level Physics. We give uncertainties to two significant figures in A-Level Physics, so the zero after the 0.01 is significant. Then we match the decimal places for the mean value (0.449 rather than 0.45).
Taking repeats should improve accuracy, but the way we calculate uncertainties in A-Level Physics is a bit too simplistic. Still, it gets students thinking about them, which is enough for now.
the zero error is not zero
Correct, it was -0.01mm
im second year engineering in uni not believing this is a-level.
oh the curse of doing an access course! gaahhhh.
great video tho thanks! I know all this gubbins through theory only!
Sincerely, it is A-Level. This is a required practical on the current syllabus, so all A-Level Physics students must do it and are assessed against five 'competencies' (the Common Practical Assessment Criteria, or CPAC). In the video, I actually fall short of the requirement for Competency 3, working safely in a laboratory 🤦♂️ but I'm not going to do it all again.
Dear Prof, please add negative zero error. Don't subtract it
Subtracting the zero error is correct. It's a negative value, so subtracting a negative value increases the measurement. Each measurement was 0.01mm too small, so subtracting negative 0.01mm is the correct approach.
@@PhysicswithKeith If I go to the gym, and would like to measure my weight. Then I see a scale, but before I get on the scale, it reads 5kg. When I got on it, it reads 70kg. I will see the 5kg as a positive error, and my real weight is 70-5=65kg. Please enlighten me Prof what my weight would be if the scale was reading a negative error of -5kg before I get on it.
@@eagle43257 if the zero error on the balance is +5kg, you subtract +5kg from the mass measurement. If the zero error on the balance is -5kg, you subtract -5kg.
If your mass is 65kg, then a +5kg zero error would cause the measurement to be 70kg. 70kg subtract positive 5kg is 65kg.
If your mass is 65kg, then a -5kg zero error would cause the measurement to be 60kg. 60kg subtract negative 5kg is 65kg.
You always subtract the zero error.
@@PhysicswithKeith Now I understand that we are saying thesame thing in different perspectives. Thank you very much for this. Thank you for your time