3.1 Quantities and Units in Mechanics

• What is a physical quantity?

  A measurable property
• What are the base quantities in mechanics?

  Mass, length, time
• The velocity of an object is a base quantity.

  False
• Match the base quantity with its SI unit:

  Mass ↔️ Kilogram

  Length ↔️ Meter

  Time ↔️ Second
• Using the correct SI units is essential for unambiguous measurements in mechanics.


  True
• Steps to convert 500 meters to kilometers:

  1️⃣ Identify the conversion factor: 1 km = 1000 m

  2️⃣ Set up the conversion: $500 \, \text{m} \times \frac{1 \, \text{km}}{1000 \, \text{m}}$

  3️⃣ Calculate the result: 0.5 km
• Match the conversion with its factor:

  Meters to Kilometers ↔️ 1 km = 1000 m

  Grams to Kilograms ↔️ 1 kg = 1000 g

  Hours to Seconds ↔️ 1 hour = 3600 s
• What are physical quantities measured in?

  Numbers and units
• What are the three base quantities in mechanics?

  Mass, length, time
• The standard SI units ensure clear and standardized measurement of physical quantities
• What is the result of converting 500 meters to kilometers?

  0.5 km
• Physical quantities are measured using numbers and units
• Derived quantities are expressed in terms of base quantities.
• What is the SI unit for mass?

  Kilogram
• What is the SI unit for velocity?

  m/s
• What is a conversion factor used for?

  Converting between units
• Always use conversion factors that allow the original unit to cancel out
• Steps to convert 500 meters to kilometers:

  1️⃣ Start with 500 meters

  2️⃣ Multiply by the conversion factor 1 km / 1000 m

  3️⃣ Cancel out the meter unit

  4️⃣ Calculate the result as 0.5 km
• It is essential to specify the unit to make a physical quantity meaningful
• Base quantities are fundamental properties that cannot be expressed in terms of other quantities
• What expresses the equivalence between two units?

  Conversion factor
• Always use conversion factors that allow the original unit to cancel out.

  True
• What is the velocity of an object that moves 2 kilometers in 10 minutes in meters per second?

  3.33 m/s
• Base quantities can be expressed in terms of other quantities.

  False
• Match the base quantity with its symbol:

  Mass ↔️ m

  Length ↔️ l

  Time ↔️ t
• The SI unit for length is the meter.
• The SI unit for acceleration is m/s^2.
• A conversion factor expresses the equivalence between two units.
• Understanding unit conversion is essential in mechanics.


  True
• Always use conversion factors that allow the original unit to cancel
• Base quantities can be expressed in terms of other quantities.

  False
• Match the base quantity with its SI unit:

  Mass ↔️ kilogram (kg)

  Length ↔️ meter (m)

  Time ↔️ second (s)
• Steps to convert 500 meters to kilometers:

  1️⃣ Start with 500 meters

  2️⃣ Multiply by the conversion factor 1 km / 1000 m

  3️⃣ Cancel out the meter unit

  4️⃣ Calculate the result as 0.5 km
• Calculate the velocity in meters per second if an object moves 2 kilometers in 10 minutes