Physics - term 1 test

DR SCCID for methods

Data collection method/equipment, Repeats, Safety/risk assessment (at least 2), Control/comparison test, Independent variable, Dependent variable, BE SPECIFIC

validity

whether an experiment is fair —> actually testing aim and purpose

ACER

Aim tested, Controlling variables, Equipment is suitable, Range of independent variables

Impact of reliability and accuracy on validity

Must be both accurate and reliable otherwise method isn’t valid choice to test hypothesis

Reliability

Reproducibility/consistency of results

Factors effecting reliability

Repeated at least twice and results averaged to either minimize effect of or disregard random errors

repetition will only…

determine reliability not improve it

outliers should only be disregarded if there is…

an obvious reason that does not bring validity of experiment into question

accuracy

dependent on design of experiment (validity of method) and sensitivity of equipment

results are accurate if they

are close to true value of quantity being measured, can be substantiated in secondary sources

Newton’s first law

inertia —> will stay at rest or constant movement unless unbalanced force —> terminal velocity

Newton’s 2nd law

F=ma —> why sky diver slows down with air resistance because magnitude of net force decreased therefore acceleration decreased

Newton’s 3rd law

Karma —> every action has an equal and opposite one —> why air resistance increases with speed because air particles hit harder up and more/ second

analysis of data

description of trend and explanation of trend supported by calculated values e.g. gradient and potential known physics principles

evaluation of data

accuracy (compared with known value), reliability (spread around line of best fit and consistency of repeats), validity and sources of error w/ suggested improvements

convert between m/s and km/h

multiply by 3.6

convert between km/h and m/s

divide by 3.6

systematic error

consistent and reproducible if experiment is repeated the same way —> method flawed or instruments not calibrated correctly

random error

unpredictable and generally not reproducible e.g. blow of wind pushing pendulum —> not method

gradient of velocity time graph

is acceleration of object

area under velocity time graph

displacement of object

area under acceleration time graph

change in velocity of object

if position time graph is curved (velocity is non uniform)

gradient of the tangent at a point gives instantaneous velocity

variables that change in linear or direct proportion to each other

produce a straight trend line

variables that change exponentially in proportion to each other

produce a curved trend line

inverse relationship

one variable increases whilst other decreases

no relationship between two variables

one variable will not change if other does

independent and dependent on graph

x = independent, y = dependent

experimental error

any error in an experiment, difference between true value and actual value

pentatick

group of 5 gaps which = to 0.1 second

time for one gap on ticker tape

0.02 seconds

evaluate reliability with difference from average

result x/ average x100= % from average