Physics AT1 flashcards

Units for measurement

Agreed quantities used in measurements, with base units in the International System of units (SI units) like second, metre, kilogram, ampere, kelvin, mole, and candela.

Derived units

Units that are based on base units, like acceleration (a = ∆v/t), force (F = ma), area (A = lw), volume (V = lwh), and work (W = Fd).

SI prefixes

Significant figures

A number that is correct within some stated degree of accuracy.

Scientific notation & orders of magnitude

Notation that represents large or small numbers as powers of ten, with orders of magnitude indicating the nearest power of ten for a number.

Linear regression

A technique used to analyse data by fitting them to a straight line.

Line of Best Fit

A method used to estimate the trend of data points by drawing a line that represents the general direction of the data.

Gradient

The slope of the line of best fit, representing the rate of change of the dependent variable concerning the independent variable.

Systematic Error

An error that consistently affects measurements in the same direction, which is usually caused by improperly calibrated reading instruments.

Random Error

An error that randomly affects measurements in random directions, and is usually caused by uncontrolled variables or random fluctuations in working conditions.

Linear Regression

A method to establish or verify relationships by fitting a straight line to data points.

Uncertainty

The margin of error or doubt associated with a measurement, often expressed as ±Δx to indicate the range within which the true value is expected to lie - MUST BE ONE SIGNIFICANT FIGURE.

Uncertainty for analogue devices

± ½ the limit of reading.

Uncertainty for digital devices

± the smallest increment.

Uncertainty in a set of data

± maximum difference from mean.

Reliability

An extent which repeated observations and/or measurements taken under identical circumstances will yield similar results.

Validity

An extent to which tests measure what was intended; an extent to which data, inferences and actions produced from tests and other processes are accurate.

Procedure vs method

Procedure - present tense

Method - past tense

Practical investigations

An investigation that involves systematic scientific inquiry by planning a course of action and using equipment to collect data and/or information. They include a range of hands-on activities and can include laboratory investigations and fieldwork.

Primary sources/primary data

Information created by a person or persons directly involved in a study or observing an event.

Variable

A factor that can be changed, maintained or measured - examples include quantities such as time, distance, light and temperature.

Independent variable

A variable that is changed in an investigation to see what effect it has on the dependant variable - plotted on horizontal axis.

Dependant variable

A variable that changes in response to to changes in the independent variable in an investigation - plotted on vertical axis.

Controlled variable

A variable that is kept constant (or changed in constant ways) during an investigation.

Validity judgement format

“As we only changed the <independent variable> and measured the <dependant variable> whilst controlling all other variables such as <variable1, variable 2, etc>, we ensured that we tested our aim of <aim>. This meant our experiment had high validity.”

Hypothesis

A tentative explanation for an observed phenomenon, expressed as a precise and unambiguous statement that can be supported or refuted by investigation.

Hypothesis format

“If the <independent variable> is <increased/decreased>, then the <dependant variable> will <increase/decrease>”

Aim format

“To determine the effect of <increasing/decreasing> the <independent variable> on the <dependent variable> for <whatever we are using to investigate this relationship>”

Title format

“The Effect of the <independent variable> on the <dependant variable> for <what we were using>”

Conclusion

A judgement based on evidence - Should be a brief statement that summarises your experimental findings that refer back to he aim and hypothesis, max 2 sentences.

Addition and subtraction of measured data

When adding or subtracting measured quantities, the final answer should have the least number of DECIMAL PLACES in the original data you used.

Multiplication and division of measured data

When multiplying or dividing measured quantities, the final answer should have the least number of SIGNIFICANT FIGURES in the original data you used.

Table format

Common sources of error

• Incomplete definition (systematic or random)

• Failure to account for a factor (usually systematic)

• Environmental factors ((systematic or random)

• Instrument resolution (random)

• Calibration (systematic)

• Zero offset (systematic)

• Physical variations (random)

• Parallax (systematic or random)

• Instrument drift (systematic)

• Lag time (systematic)

Extrapolation

Extending the line of best fit forward using a dashed line to estimate data.

Versus graph format

“<Variable on vertical axis> vs <variable on horizontal axis> for <what you are using to investigate this relationship>”

Percentage error

Parabolic curve

Equation A = k * Bⁿ

Lineaized A = k * ⁿ√B

Root curve

Equation A = k * ⁿ√B

Lineaized A = k * Bⁿ

Inverse or hyperbolic curve

Equation A = k * B^-n

Linearized A = k * B^-1/n

Secondary-sourced information

An investigation that involves systematic scientific inquiry by planning a course of action and sourcing data and/or information from other people, including written information, reports, graphs, tables, diagrams and images.

APA general format

Author(s), (Year of Publication). Title (edition), Place of Publication, Publisher

---

Eg: Drew, P., & Horden, P.T., (2008). New Tent Architecture (2nd ed.). London: Thames & Hudson.

Internal reliability

When repeated trials within an experiment are consistent. This is sometimes also called precision.

External reliability

When the results from one experiment are consistent with those from other experiments that are conducted the same way.

Reliability judgement format

“For each <independent variable>, we <measurement of dependant variable>. The <results from dependent variable> were recorded and compared until there was <No. of trials> consistent <dependent variable> (any outliers were removed) Once <No. of trials> have been achieved, <change in independent variable> and the process repeated until <No. of trials> more consistent <dependent variable> were achieved from the new <independent variable>. Once <No. of trials> consistent <Dependant variable> were achieved for <every change in dependant variable> then the <results for dependant variable> were averaged. This ensured high reliability of our measured data.”