Chapter 1 · Physical quantities & measurement
Measure first.
Reason precisely.
Read instruments correctly, improve tiny measurements using multiples, time oscillations, distinguish scalars from vectors and construct perpendicular resultants.
Investigation 1
Measure length and volume
Use a ruler and measuring cylinder, read scales at eye level and use displacement for an irregular object.
Investigation 2
Measure a time interval
Choose a suitable clock or digital timer and measure from a defined start event to a defined finish event.
0.00 s
Investigation 3
Measure multiples, then average
Reduce percentage uncertainty by measuring many small distances or time intervals together.
Thickness of one sheet
6.0 mm
one sheet = 6.0 ÷ 50 = 0.120 mm
Period of a pendulum
total time ÷ number of oscillations = period
Measuring many repeats makes the fixed reading or reaction-time uncertainty a smaller fraction of the total.
Investigation 4
Classify scalars and vectors
A scalar has magnitude only. A vector has magnitude and direction.
Investigation 5 · Supplement
Find the resultant of perpendicular vectors
Determine the magnitude and direction by scale drawing or by Pythagoras and trigonometry.
Assessment
Check every objective
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