physics

Physical Quantity

is a quantity that can be defined and measured.

Has both a number and a unit
👉 Example: 153 cm

📎 Examples:
Length, Mass, Time, Temperature, Electric Current, Amount of Substance, Volume

BASE QUANTITY

Fundamental physical quantities that are independent of others and serve as the foundation for deriving other quantities.

DERIVED QUANTITY

Physical quantities that are calculated from base quantities by multiplication or division.
They cannot be measured directly.

SI UNITS

International System of Units — the global standard for measurement, also known as the metric system.

Used worldwide in science and daily life for consistent physical measurements.

• Meter (m) – Length

• Kilogram (kg) – Mass

• Second (s) – Time

• Kelvin (K) – Temperature

• Ampere (A) – Electric current

prefix

are added to SI units to show multiples or submultiples of a measurement.

🧠 Key Idea:
They make it easier to express very large or very small values.

📎 Examples:

• kilo- (k) = 1,000

• centi- (c) = 1/100

• milli- (m) = 1/1,000

• mega- (M) = 1,000,000

• micro- (μ) = 1/1,000,000

SCIENTIFIC NOTATION

A way to write very large or very small numbers using powers of 10.

🧠 Key Use:
Commonly used in science and math for simplicity and accuracy.

Significant Figures

Digits in a number that show its precision or how exact the value is.

🧠 Key Use:
Used in scientific and mathematical measurements.

Accuracy

is how close a measurement is to the correct or true value.
🧠 Think: hitting the bullseye on a dartboard!

Precision

is how close repeated measurements are to each other.
🧠 Think: all darts landing in the same spot, even if it’s not the bullseye!

measurement

is the act of finding out the size, length, weight, or capacity of something.
We do this by comparing it to standard values to make sure it’s accurate and precise.

unit of measurement

is a standard amount used to describe physical quantities.

🌍 There are two main systems used around the world:

• Metric Units (like meters, grams)

• English Units (like inches, pounds)

Length

tells us how long something is from one end to the other.

Mass

is the amount of matter something is made of.

Time

is the continuous flow of events — from past to present to future.