Physical Quantities and Units – Key Concepts (Video Notes)

Flashcards covering physical quantities, units, prefixes, scientific notation, unit conversion, and basic vector concepts as presented in the video notes.

What is a physical system?

Objects being affected by what goes on around them.

What are physical properties?

Properties that an object has which can be measured (e.g., diameter, surface area, volume, mass, speed, position).

What is a mathematical equation in physics?

A way of relating physical properties; examples include Area = length × width and Speed = distance ÷ time.

What are units?

Numbers attached to measurements that specify the scale of the quantity.

What are the standard international (SI) units for length and speed?

Length: meter (m); Speed: meters per second (m/s).

What does 'Different measuring system' mean?

The numbers and units used to describe a measurement change depending on the system you use

What are the major systems of units?

SI units (International System of Units)

CGS units (Centimeter-Gram-Second)

and English units (Imperial or US Customary units).

What is the difference between fundamental and derived quantities?

Fundamental quantities cannot be derived from others . Derived quantities can be derived from fundamental ones.

What are the base units for Length in SI, CGS, and BE?

SI: meter (m); CGS: centimeter (cm); BE: foot (ft).

What is the base unit for Mass in SI, CGS, and BE?

SI: kilogram (kg); CGS: gram (g); BE: slug (sl).

What is the base unit for Time in these systems?

Second (s) in SI, CGS, and BE.

What are derived units?

Units obtained from the mathematical formulas that relate quantities (e.g., Area, Volume, Speed, Density).

What is the SI base unit for Area?

Square meter (m^2).

What is the SI base unit for Volume?

Cubic meter (m^3).

What is the SI unit for Average speed?

Meters per second (m/s).

What is the SI unit for Density?

Kilograms per cubic meter (kg/m^3).

What are metric prefixes used for?

To denote factors of 10 (e.g., 1 km = 10^3 m; 1 cm = 10^-2 m).

List some metric prefixes and their powers of 10.

• Tera (T): 10^{12}- Giga (G): 10^9- Mega (M): 10^6- Kilo (k): 10^3- Hecto (h): 10^2- Deka (da): 10^1- Deci (d): 10^{-1}- Centi (c): 10^{-2}- Milli (m): 10^{-3}- Micro (μ): 10^{-6}- Nano (n): 10^{-9}- Pico (p): 10^{-12}- Femto (f): 10^{-15}

What is scientific notation?

A number between 1 and 9 multiplied by a power of 10.

Express 100 cm in scientific notation.

1.00 × 10^2 cm.

Express 1,000,000,000 GBytes in scientific notation.

1 × 10^9 GBytes.

What are the steps to convert units for the same quantity?

1) List the units you have and the units you want to convert to; 2) Determine a conversion factor; 3) Multiply so unwanted units cancel out.

Convert 80 m to km.

0.08 km.

Convert 300 ft^3 to m^3 (use 1 ft ≈ 0.30 m).

8.1 m^3.

Convert 0.5 miles to meters (1 mile ≈ 1609 m).

804.5 m.

What is a scalar quantity?

A quantity described only by a magnitude (e.g., mass = 5 kg).

What is a vector quantity?

A quantity described by both magnitude and direction (e.g., a car moving north at 60 mph).

How is a vector graphically represented?

As an arrow with a tail and a head; vectors are written with a symbol (usually a letter) and an arrow above it.

What do tail and head of a vector represent?

Tail is the starting point of the vector; head is the end point.

What is the head-to-tail method for vector addition?

1) Draw the first vector; 2) Place the tail of the next vector at the head of the previous one; 3) Repeat; 4) Draw the resultant from the tail of the first to the head of the last.

What is the resultant vector in the head-to-tail method?

The vector from the tail of the first vector to the head of the last vector.

What is the result of adding 2 cm east and 3 cm east using the head-to-tail method?

5 cm east.

How is a vector notation typically shown?

With an arrow over the symbol (e.g., r⃗) or bold face for the vector quantity.