Besaran Pokok and Turunan

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your exam.

Topic 3 for UNDANA Admission Saintek centres on besaran, satuan, dan pengukuran — the vocabulary every later Physics, Chemistry, and Biology question depends on. A besaran pokok is defined independently (length, mass, time, temperature, amount of substance, electric current, luminous intensity); a besaran turunan is built by combining them. The seven SI base quantities give all derived units used in UNDANA Saintek numerics.

Memorise these relations and their unit symbols:

Quantity	Formula	SI unit	Symbol
Speed	v = s / t	metre per second	m/s
Density	rho = m / V	kilogram per cubic metre	kg/m³
Force	F = m · a	newton	N
Weight	W = m · g	newton	N
Pressure	P = F / A	pascal	Pa

Exam pointers: convert all values to SI before computing; mass (kg) ≠ weight (N); pressure needs area in m², not cm².

🟡 Standard — Regular Study (2d–2mo)

Standard content for students with a few days to months.

Besaran Pokok and Turunan

The seven besaran pokok carry fixed SI symbols and must never be confused with their derived counterparts. Length (m), mass (kg), and time (s) recur in every UNDANA Saintek numeric. Besaran turunan such as velocity, acceleration, force, work, and pressure are expressed in derived units (m/s, m/s², N, J, Pa). A frequent trap: examiners list mass (kg) next to weight (N) in a table and ask which row is a pokok quantity — only mass qualifies.

Pengukuran dan Angka Penting

Read a jangka sorong by adding the main-scale millimetre reading to the nonius scale (typically 0.01 cm resolution). A mikrometer sekrup adds the sleeve reading to the thimble scale × its pitch (usually 0.01 mm). Every recorded digit, including one estimated digit, counts as an angka penting. Multiplication must keep the answer to the same number of significant figures as the least precise factor.

Ketidakpastian

For repeated measurements, the ketidakpastian relatif is half the instrument’s smallest division divided by the mean reading, expressed as a percentage. Lower relative uncertainty means higher data quality — examiners test this when a longer decimal answer is demanded than the instrument can justify.

Worked relationships

A 2.0 kg block on Earth: W = m · g = 2.0 × 9.8 = 19.6 N.
A 0.50 m × 0.50 m plate under 100 N: A = 0.25 m², so P = 100 / 0.25 = 400 Pa.

Tip: write units at every step — leaving “g” off mass or “m²” off area is the most common single-error deduction in UNDANA Saintek.

🔴 Extended — Deep Study (3mo+)

Comprehensive coverage for students on a longer study timeline.

Dimensional consistency as a check

Before trusting any answer, perform a dimensional audit. For v = s / t: m / s. For P = F / A: N / m² = kg·m⁻¹·s⁻². If your final unit does not collapse to the expected SI form, the calculation contains an algebraic slip. This skill transfers to UNDANA Saintek Chemistry stoichiometry (mol, g/mol) and Biology rate problems (mL/s).

Edge cases examiners exploit

Mass vs weight in other contexts: a 5 kg object on the Moon (g ≈ 1.6 m/s²) weighs 8 N, not 50 N. The mass is unchanged; weight scales with local g.
Significant figures in chains: when intermediate steps are written down, round only at the final answer, otherwise rounding error compounds.
Unit prefixes: µ (micro, 10⁻⁶), m (milli, 10⁻³), k (kilo, 10³) — converting 250 mL to SI yields 2.5 × 10⁻⁴ m³, not 0.00025 m³ written carelessly.
Variable classification in metode ilmiah: identify variabel bebas (manipulated), variabel terikat (responding), and variabel kontrol (held constant); UNDANA Saintek HOTS items embed these inside a paragraph of experimental context.

Connections to later topics

Density (rho = m / V) underpins Archimedes’ principle and solution concentration. Pressure (P = F / A) sets up hydraulics and barometry. Newton’s second law (F = m·a) introduces momentum and energy chapters, so a Topic-3 mastery compounds across the entire UNDANA Saintek paper.

Trap to avoid: P = F / A gives pressure, not force — students occasionally invert it during time pressure.

Practice prompts

A cylinder of mass 3.6 kg rests on a circular base of radius 5.0 cm. Compute the pressure exerted, in Pa, using g = 9.8 m/s². (Answer: ~4.6 × 10³ Pa.)
A ruler’s smallest division is 1 mm. The mean of five length readings is 24.6 mm. State the absolute uncertainty and the relative uncertainty in percent.

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Besaran Pokok and Turunan