How are the various uncertainties calculated?

I know how to calculate range/n, I think that's random error.

But what about percentage and absolute error? Maybe it would be easier if someone solved Q1 from 2003.

## Uncertainties

### Vixus

Posted 14 May 2006 - 11:33 AM

Acceleration of a car is measured. Following data gathered:

s = 3.54 +- 0.01m

t = 2.53, 2.29, 2.34, 2.36, 2.65, 2.53 s

a = 2s/t

Calculate random uncertainty in time measurement.

Calculate % uncertainty in average acceleration.

Express numerical result in form

final value +- absolute uncertainty

s = 3.54 +- 0.01m

t = 2.53, 2.29, 2.34, 2.36, 2.65, 2.53 s

a = 2s/t

^{2}Calculate random uncertainty in time measurement.

Calculate % uncertainty in average acceleration.

Express numerical result in form

final value +- absolute uncertainty

### Pringles

Posted 14 May 2006 - 03:18 PM

Here is how I done this.

Average time firstly is = 2.45 seconds

Average acceleration =

Random uncertainty =

Percentage uncertainty in distance =

= +/- 0.28%

Since this value is less than a third of the percentage uncertainty in time then it can be ignored.

Therefore uncertainty in = +/- 4.9%

so in numerical form = 1.18 +/- 0.06m/s/s

Average time firstly is = 2.45 seconds

Average acceleration =

Random uncertainty =

Percentage uncertainty in distance =

= +/- 0.28%

Since this value is less than a third of the percentage uncertainty in time then it can be ignored.

Therefore uncertainty in = +/- 4.9%

so in numerical form = 1.18 +/- 0.06m/s/s

### skint_student

Posted 14 May 2006 - 09:14 PM

yeah that looks about right.

you could work out the standard deviation for the random error but I dunno if that is required in advanced higher. Max - min divided by number of readings is probably fine.

you could work out the standard deviation for the random error but I dunno if that is required in advanced higher. Max - min divided by number of readings is probably fine.