📘 Top Formulas & Quick Revision
for Measurements
This cheat-sheet helps you revise important formulas and key facts from the chapter “Physical Quantities and Measurement” for Class 8 IIT Foundation.
🔹 Fundamental Concepts
- Measurement: Comparing an unknown quantity with a known standard unit.
- Physical Quantity: A measurable quantity like length, mass, time, etc.
- Unit: A standard used to express a physical quantity.
- SI Units: Standard International units used worldwide for consistency.
🔹 Commonly Used Units and Symbols
- Length – metre (m)
- Mass – kilogram (kg)
- Time – second (s)
- Temperature – kelvin (K)
- Electric Current – ampere (A)
🔹 Prefixes in SI Units
Kilo (k) = 10³
Centi (c) = 10⁻²
Milli (m) = 10⁻³
Micro (μ) = 10⁻⁶
Nano (n) = 10⁻⁹
🔹 Top Formulas You Must Know
Speed = Distance ÷ Time
Density = Mass ÷ Volume
Area of Rectangle = Length × Breadth
Volume of Cube = Side³
Volume of Cuboid = Length × Breadth × Height
Time Period (Simple Pendulum) = 2Ï€ √(L/g)
🔹 Conversion Tips
- 1 km = 1000 m
- 1 m = 100 cm
- 1 cm = 10 mm
- 1 kg = 1000 g
- 1 hour = 3600 seconds
🧠Remember: Always convert quantities to SI units before applying formulas!
🔹 Important Terms
- Least Count: Smallest measurement a device can read.
- Accuracy: Closeness to the actual value.
- Precision: Repeatability or consistency of results.
- Error: Difference between the measured and true value.
