You gain from accurate measurements

TO MEASURE IS TO KNOW

Eyes (seeing)

Ears (hearing)

Nose(smelling)

Mouth(tasting)

Skin (feeling)

inaccurate!!

NASK – WAARNEMEN VS METEN

Senses1

temperature thermometertime clock,

stopwatchlength rulerweight scales

more accurate than senses!!

Measuring instruments2

Inaccurate: Accurate:Repeated measurements Repeated measurementskeep giving different keep giving the same valuesvalues.

Accuracy4

Imprecise: Precise:Measurements are not on Measurements are close tothe actual value the actual value

Precise5

One measurement alone says nothing about accuracy or precision

No. of measurements3

examples Stopwatch test one measurement

largeClassic stopwatch test

Accuracy can depend on:

The accuracy of the measuring instruments.

The number of measurements.

The accuracy with which they are used.

The accuracy with which the researcher reads the instrument

In research the accuracy of measurements is

essential/important

Accuracy of measuring

School rulerat 1 cm accuracy ± 0.5 cm

Metal rulerat 1 mm accuracy ± 0.5 mm

Caliper

at 0.1 mm accuracy ± 0.05 mm  

Density practical

Mass (m) iron = 35.4 g Volume (V) iron = 3 x 1 x 1.5 = 4.5 cm³

Accuracy of calculation

The accuracy depends, among other things, on the scale.

The step size is a measure for dividing the scale.

Division of Scale

Step of

0.5

0.1

0.1

Division of ScaleYou make a division of scale by dividing the distance between minimal and maximal values in equal pieces of logical value.

Accuracy of calculation Density practical

Mass iron = 35 g Volume iron = 3 x 1 x 1.5 = 5 cm³

Accuracy of calculation 3 cm is different to 3.0 cm

The value of 3 is rounded to a value between 2.5 and 3.49

The value of 3.0 is rounded to a value between 2.95 and 3.049

Reading the measuring cylinder