Unit E

units of measurements, reliability of a measurement, sig figs in calculations, density, energy and its units, converting between units, problem-solving strategies

What are the 7 S.I Units

mass, time, temperature, amount of substance, electric current, light intensity, length

Mass

Kilogram(kg); quantity of matter

Time

Seconds(s); how long

Temperature

Kelvin(K); how hot

Amount of Substance

Mole(mol); amount

Electric Current

Ampere(A); flow of electrons

Light Intensity

Cavdela(Cd); firework

Length

Meters(m); how long in distance

What is a measurement

quantitative observation with numbers and a unit

Derived Units

volume, density, speed, acceleration, force, energy, pressure

Volume

LWH

Density

mass/volume(kg/m³)

Speed

length/time(m/s)

Acceleration

speed/time or length/time²(m/s²)

Force

mass x acceleration (kg(m/s²) newtons (N)

Energy(using force and distance)

force x distance (kg(m²/s²)) joules (J)

Energy(using mass and speed)

mass x speed² (kg(m²/s²)) joules (J)

Pressure

force/area (kg/ms²) pascal (PA)

Order of Prefixes from smallest to largest

pico → nano→ macro → milli → 1 → kilo → mega → giga → tera

Sig Fig Basic Rules

1. all non zero digits are significant

2. zeros need special attention

   a. leading zeros are not significant

   b. captive zeros are not significant

   c. trailing zeros before or after a decimal are significant

   d. trailing zeros without a decimal is ambiguous and must be vaoided by converting to scientific notation

3. exact numbers are infinity(Ex. 25 students, infinite sig figs)

4. defined quantitative, unit conversion

Sig Fig Multiplication and Division Rules

report to least number of sig figs

Sig Fig Addition and Subtraction Rules

report to the least decimal place(NOT SIG FIG)- because you may lose or gain good digits