Calculating Uncertainty when Converting Time

  • Thread starter Thread starter ELLE_AW
  • Start date Start date
  • Tags Tags
    Time Uncertainty
AI Thread Summary
The discussion focuses on converting time from minutes to hours while calculating the associated uncertainty. The initial calculation shows that 10 minutes converts to 0.167 hours, with an uncertainty derived as 0.0000334 hours. However, confusion arises regarding the correct representation of uncertainty, as the contributor realizes that 0.2 minutes is actually 2% of 10 minutes, not 0.02%. A more straightforward approach suggested is to convert the uncertainty directly from minutes to hours, resulting in an uncertainty of 0.003 hours. The conversation highlights the importance of correctly calculating and representing uncertainty in measurements.
ELLE_AW
Messages
16
Reaction score
0

Homework Statement


The problem asks to convert time in minutes to time in hours, and to also calculate the uncertainty for the time in hours.Specifically 10 minutes +/- 0.2min being converted to hours with uncertainty.

2. Homework Equations & 3.The attempt at a solution

conversion of time:
10.0 min x 1h/60 min = 0.167h

uncertainty of time in hours:
- 1/60 is a conversion factor, and has an uncertainty of zero
- When multiplying, you're supposed to calculate the percent uncertainty of each measure and add them up to get the percent uncertainty of the product. Then, you can apply that percent uncertainty to the product to see what the uncertainty would be.

So I did the following:

time in minutes ± 0.2 (min), therefore 0.2min/10min = 0.02%

1/60 is a conversion factor, and has zero uncertainty

Therefore, 0.02% + 0% = 0.02%, which can now be applied to the product of the sample calculation for time in hours:

0.167 x 0.02% = 0.0000334

so time in hours = 0.167 +/- 0.0000334

This answer just doesn't make sense to me though. First of all the number of decimal places between the measurement and the uncertainty don't match or even come close.

I feel like a more likely answer would be to just convert 0.2 min (the uncertainty of time in minutes) to hours ( 0.2 min x 1h/60min = 0.003h) and then just have that be the uncertainty for hours, since the conversion factor does not play any role here.

So my final answer would be Time in Hours:
0.167 h +/- 0.003I've BOLDED both of my answers. Which one do you guys think makes more sense and why?

Thanks
 
Physics news on Phys.org
0.2 is 2 % of 10, not 0.02 %.
 
Orodruin said:
0.2 is 2 % of 10, not 0.02 %.
Hahaha, oh wow. I'm definitely tired today. That explains everything. Thanks!
 
Sometimes you stare at a problem for so long that the obvious solution becomes invisible to you...
 
  • Like
Likes ELLE_AW
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top