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When physical quantities are added or substracted, errors of observation are always added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

L + b + t = (10.64 + 4.46 + 1.98) cm +/- 0.03 cm = 17.08 +/-0.03 cm

L - b + t = (10.64 - 4.46 + 1.98) cm +/- 0.03 cm = 8.16 +/-0.03 cm

When physical quantities are multiplyed or devided, percentage errors of measured are added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

Percentage uncertainty of L = (0.01/10.64) x 100 = 0.09%

Percentage uncertainty of b = (0.01/4.46) x 100 = 0.22%

Percentage uncertainty of L = (0.01/1.98) x 100 = 0.50%

L x b x t = (10.64 x 4.46 x 1.98) cm3 +/-(0.09 + 0.22 + 0.50)% = 93.96 cm3 +/-0.81% = 93.96 cm3 +/-0.76cm3

L / (b x t) = 10.64 /(4.46 x 1.98) cm-1 +/-(0.09 + 0.22 + 0.50)% = 1.20 cm-1 +/-0.81% = 1.20 cm-1 +/-0.0097cm-1

When physical quantities are squared, cubed, ..... etc, percentage errors of measured quantities are doubled, trebled, ..... etc.

Eg:

I'm sorry I can't give an example because I can't type powers. If you need more clarification, PM me.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

L + b + t = (10.64 + 4.46 + 1.98) cm +/- 0.03 cm = 17.08 +/-0.03 cm

L - b + t = (10.64 - 4.46 + 1.98) cm +/- 0.03 cm = 8.16 +/-0.03 cm

When physical quantities are multiplyed or devided, percentage errors of measured are added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

Percentage uncertainty of L = (0.01/10.64) x 100 = 0.09%

Percentage uncertainty of b = (0.01/4.46) x 100 = 0.22%

Percentage uncertainty of L = (0.01/1.98) x 100 = 0.50%

L x b x t = (10.64 x 4.46 x 1.98) cm3 +/-(0.09 + 0.22 + 0.50)% = 93.96 cm3 +/-0.81% = 93.96 cm3 +/-0.76cm3

L / (b x t) = 10.64 /(4.46 x 1.98) cm-1 +/-(0.09 + 0.22 + 0.50)% = 1.20 cm-1 +/-0.81% = 1.20 cm-1 +/-0.0097cm-1

When physical quantities are squared, cubed, ..... etc, percentage errors of measured quantities are doubled, trebled, ..... etc.

Eg:

I'm sorry I can't give an example because I can't type powers. If you need more clarification, PM me.

yea do it dat way..bt wteva uve already done is greatly appreciated. thnx man!!!

Goddess

When physical quantities are added or substracted, errors of observation are always added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

L + b + t = (10.64 + 4.46 + 1.98) cm +/- 0.03 cm = 17.08 +/-0.03 cm

L - b + t = (10.64 - 4.46 + 1.98) cm +/- 0.03 cm = 8.16 +/-0.03 cm

When physical quantities are multiplyed or devided, percentage errors of measured are added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

Percentage uncertainty of L = (0.01/10.64) x 100 = 0.09%

Percentage uncertainty of b = (0.01/4.46) x 100 = 0.22%

Percentage uncertainty of L = (0.01/1.98) x 100 = 0.50%

L x b x t = (10.64 x 4.46 x 1.98) cm3 +/-(0.09 + 0.22 + 0.50)% = 93.96 cm3 +/-0.81% = 93.96 cm3 +/-0.76cm3

L / (b x t) = 10.64 /(4.46 x 1.98) cm-1 +/-(0.09 + 0.22 + 0.50)% = 1.20 cm-1 +/-0.81% = 1.20 cm-1 +/-0.0097cm-1

When physical quantities are squared, cubed, ..... etc, percentage errors of measured quantities are doubled, trebled, ..... etc.

Eg:

I'm sorry I can't give an example because I can't type powers. If you need more clarification, PM me.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

L + b + t = (10.64 + 4.46 + 1.98) cm +/- 0.03 cm = 17.08 +/-0.03 cm

L - b + t = (10.64 - 4.46 + 1.98) cm +/- 0.03 cm = 8.16 +/-0.03 cm

When physical quantities are multiplyed or devided, percentage errors of measured are added.

Eg:

L = 10.64 +/- 0.01 cm

b = 4.46 +/- 0.01 cm

t = 1.98 +/- 0.01 cm

Percentage uncertainty of L = (0.01/10.64) x 100 = 0.09%

Percentage uncertainty of b = (0.01/4.46) x 100 = 0.22%

Percentage uncertainty of L = (0.01/1.98) x 100 = 0.50%

L x b x t = (10.64 x 4.46 x 1.98) cm3 +/-(0.09 + 0.22 + 0.50)% = 93.96 cm3 +/-0.81% = 93.96 cm3 +/-0.76cm3

L / (b x t) = 10.64 /(4.46 x 1.98) cm-1 +/-(0.09 + 0.22 + 0.50)% = 1.20 cm-1 +/-0.81% = 1.20 cm-1 +/-0.0097cm-1

When physical quantities are squared, cubed, ..... etc, percentage errors of measured quantities are doubled, trebled, ..... etc.

Eg:

I'm sorry I can't give an example because I can't type powers. If you need more clarification, PM me.

Wow that's a lot of work! Must have taken you a lot of time to type.

This is what the NAS AS and A2 Revision Guide (for Edexcel) says about percentage uncertainties:

* Only work out uncertainties if and where the question tells you to do so, therefore for most of your measurements you won't have to bother with uncertainties.

* For a single measurement take the smallest division of the instrument as its uncertainty e.g. a length might be 19 + 1 mm using a meter rule and 18.8 + 0.1 mmusing vernier callipers.

* Practice finding percentage uncertainties (equation given in test); e.g. 5.3% and 0.53% for above lengths.

* For a set of repeated readings take half the spread of the readings as the uncertainty of the average value e.g. 1.25, 1.29, 1.28, and 1.26 mm giving a spread of 0.04 mm so average value = 1.27 + 0.02 mm with a percentage uncertainty of 1.6%.

* For measurements, such as starting and stopping a timer, where your own error adds significantly to the uncertainty, always take several measurements and use their range to get the uncertainty.

* Add the uncertainties of any measurements that are either added or substracted.

* Add the percentage uncertainties of any measurements that are multiplyed or devided.

* Multiply the percentage uncertainty by any powers to which the measurement is raised e.g. percentage error in r^3 is 3 x percentage uncertainty in r.

* Use 100 x difference/average value to calculate the percentage difference between two values.

* Only work out uncertainties if and where the question tells you to do so, therefore for most of your measurements you won't have to bother with uncertainties.

* For a single measurement take the smallest division of the instrument as its uncertainty e.g. a length might be 19 + 1 mm using a meter rule and 18.8 + 0.1 mmusing vernier callipers.

* Practice finding percentage uncertainties (equation given in test); e.g. 5.3% and 0.53% for above lengths.

* For a set of repeated readings take half the spread of the readings as the uncertainty of the average value e.g. 1.25, 1.29, 1.28, and 1.26 mm giving a spread of 0.04 mm so average value = 1.27 + 0.02 mm with a percentage uncertainty of 1.6%.

* For measurements, such as starting and stopping a timer, where your own error adds significantly to the uncertainty, always take several measurements and use their range to get the uncertainty.

* Add the uncertainties of any measurements that are either added or substracted.

* Add the percentage uncertainties of any measurements that are multiplyed or devided.

* Multiply the percentage uncertainty by any powers to which the measurement is raised e.g. percentage error in r^3 is 3 x percentage uncertainty in r.

* Use 100 x difference/average value to calculate the percentage difference between two values.

Sfteeeeeee

For those taking the A2 edexcel practical tomorrow this is from the specification:

'Candidates should take repeat readings whenever it is reasonable to do so, in which case the

percentage uncertainty should be based on the spread of the readings. The estimated uncertainty

is then half the spread.

If it only possible to take one reading, then the percentage uncertainty should be based on the

precision with which the scale can be read. The estimated uncertainty in this case is half of one

scale division.'

'Candidates should take repeat readings whenever it is reasonable to do so, in which case the

percentage uncertainty should be based on the spread of the readings. The estimated uncertainty

is then half the spread.

If it only possible to take one reading, then the percentage uncertainty should be based on the

precision with which the scale can be read. The estimated uncertainty in this case is half of one

scale division.'

- Engineering degree if bad at practical work
- Maths
- What are these a levels and their courses like?
- Higher Physics - should I take it?
- Are the CGP books good for these A level subjects?
- GCSE Physics Study Group 2023-2024
- Got an E in AQA physics mock, need help
- struggling with physics
- Entry requirements for Physics and Astrophysics degree
- possible to do AS and AL physics in 6 months ?
- Applied science unit 3
- A-Level Physics
- Edexcel A-Level Physics without practical.
- Alevel practical endorsement
- Subject Specific Websites GCSE
- how to pull off a decent grade in AS physics with 2 months left
- Will it be possible to learn the entire GCSE maths and physics curriculum in a year?
- Taking a gap year to retake a levels, tips for getting A/A*?
- Really struggling with a-levels in year 12
- gcse physics

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