Physics lesson Quantities and units Num Quantity tools

Physics lesson

Quantities and units Num Quantity tools Units Dimension 1 length ruler meter L 2 mass Balance kilogram M 3 time stopwatch second T 4 current ammeter Ampere I 5 temperature thermometer Kelvin Ө 6 Light intensity lightmeter candela J 7 Amount of matters mole N

• Dimension is the symbol to show a quantity is arranged from basic quantity • Dimension of Basic quantities: M, L, T, I, J, N and Ө • Dimension of Derivative quantities • Steps: 1. Find the formula • 2. Find the units (basic quantity) • 3. Find the dimension • Example: Find the dimension of force • the formula : F = m. a • the units : = kg. m/s 2 • the dimension : = M. L/T 2

Practice • 1. Find the dimension of ; – a. density – b. kinetic energy – c. potential energy

Energi kinetik • EK = ½ m. v 2 • = kg. (m/s)2 • = M. L 2. T-2

• 2. tentukan mana rumus yang benar v = kecepatan h = ketinggian g = percepatan gravitasi

• 3. The law of gravity is Note: F : force m: mass r : distance between the objects G : constant FIND THE UNITS OF G !

The function of Dimension: • 1. Menentukan kesetaraan suatu besaran. • 2. Menentukan kebenaran suatu rumus • 3. Menentukan satuan dari konstanta

• Scientific notation is the way to express smaller and larger number. • a x 10 n • with 1‹ a < 9 and n is the integer • Example: 0. 000036 = 3. 6 x 10 -5 • 76800000= 7. 68 x 107

Significant number is the number that gets from measurement. Consist of exact number and one predict number. The rules 1. All figures (but zero) are significant number (semua angka kecuali nol, adalah angka penting) Examples: 21. 36 gram (4 significant number) 4. 57 cm (3 significant number) 2. All zeros lie between non-zero figures are significant number. (angka nol diantara angka bukan nol adalah angka penting) Examples: 201. 06 m (5 significant number) 4. 008 Kg (4 significant number)

3. All zeros number at the right hand side of nondecimal figure must be express in scientific notation or give a special explanation with underlined (semua angka nol disebelah kanan bilangan bukan desimal perlu penjelasan khusus) Examples: 5200 mm (? significant number) 5200 mm (3 significant number) or 5, 20 x 103 mm (3 significant number) 4. All zeros used to determine the position of the decimal point are not significant number (nol disebelah kiri bilangan kurang dari 1, bukan angka penting) Examples: 0. 0067 mm (2 significant number) 0. 0308 gr (3 significant number)

5. All zeros number at the right hand side of decimal figures are significant number. (Semua angka nol di kanan bilangan desimal adalah angka penting) Example: 23. 200 cm (5 significant number) 0. 0230 cm (3 significant number)

The mathematical operation of significant numbers • • • Addition and subtraction Example: 29 500 + 6 990 = 36 490 ≈ 36 500 530 – 287 = 243 ≈ 240 • • • Multiplication and division Example: 796 x 320 = 254 720 ≈ 255 000 0. 428 : 0. 7 = 0. 6114 ≈ 0. 6

• • Power and roots Example: 3. 283 = 35. 287552 ≈ 35. 3 3. 28 = 10995. 116 ≈ 11 000 √ 196 = 14. 0

PENGUKURAN TUNGGAL X = x 0 ± Δx Δx = ½. nst

PENGUKURAN BERULANG Xi (cm) Xi 2(cm 2) 1 2, 001 4, 004001 2 2, 000 4, 000000 3 2, 001 4, 004001 Sum (∑) 6, 002 12, 008002 PENGUKURAN KE-

Menentukan volume = rusuk 1 x rusuk 2 x rusuk 3 volume = 2, 001 x 2, 000 x 2, 001 volume = 8, 008002 cm 3 volume = 8, 008 cm 3 (aturan pembulatan angka penting untuk perkalian)

Menentukan massa jenis

Contoh soal: 2, 02 8, 4 + 10, 42 jadi 10, 4 2, 02 x 8, 4 = 16, 968 = 17

Materi UH 1 BAB 2: 1. nst dan alat ukur (jangka sorong, mikrometer, neraca, stopwatch) 2. Pengukuran tunggal dan ketidakpastian 3. Pengukuran berulang dan simpangan baku 4. Dimensi besaran turunan 5. Notasi ilmiah 6. Aturan angka penting 7. Operasi hitung angka penting 8. Awalan satuan (Tera, Giga, kilo, mili, mikro, nano dst) 9. Konversi satuan ( kg/m 3 jadi g/cm 3 atau km/jam jadi m/s)