In this chapter, the following topics are important for long questions in board exams:

1. Estimation of Physical Quantities

Make reasonable estimates of the values of physical quantities (e.g., mass of a person, speed of a car, distance between cities, etc.). Explain why estimation is important in physics and how to make reasonable guesses based on everyday experiences.

2. SI Units and Conventions

Explain the International System of Units (SI). Use the conventions for indicating units as set out in the SI units. Describe the seven base quantities and their base units (meter, kilogram, second, ampere, kelvin, mole, candela).

3. Derived Units

Express derived units as products or quotients of the SI base units. Give examples of derived units such as newton (kg m s⁻²), joule (kg m² s⁻²), watt (kg m² s⁻³), pascal (kg m⁻¹ s⁻²), etc. Show how to derive these units from basic formulas.

4. Dimensional Analysis – Homogeneity of Physical Equations

Analyze the homogeneity of physical equations through dimensional analysis. Explain that for an equation to be correct, the dimensions on both sides must be the same. Show how to check if an equation is dimensionally correct.

5. Dimensional Analysis – Deriving Formulae

Derive formulae in simple cases using dimensional analysis. Show how to find the relationship between physical quantities by using their dimensions. For example, derive the formula for time period of a pendulum or drag force.

6. Accuracy and Precision

Analyze and critique the accuracy and precision of data collected by measuring instruments. Explain the difference between accuracy (how close a measurement is to the true value) and precision (how consistent repeated measurements are).

7. Uncertainty in Measurements

Explain why all measurements contain some uncertainty. Assess the uncertainty in a derived quantity by simple addition of absolute, fractional, or percentage uncertainties. Show how to add uncertainties when quantities are added, subtracted, multiplied, or divided.

8. Scientific Notation

Quote answers with correct scientific notation. Explain how to express very large or very small numbers using scientific notation. Give examples: 0.00035 = 3.5 × 10⁻⁴, 3500000 = 3.5 × 10⁶.

9. Significant Figures

Quote answers with the correct number of significant figures. Explain the rules for determining significant figures and how to round off answers to the appropriate number of significant figures.