Physical Quantities – Fundamental and Derived - UNSOLVED PRACTICE SET

Q7. Define a physical quantity. Distinguish between fundamental and derived quantities with one example of each.

Q8. List the seven fundamental quantities in the SI system along with their SI units and symbols

Q9. Is "amount of substance" a fundamental quantity? If yes, what is its SI unit? Why is it important in chemistry and physics?

Q10. Your physics lab has a metre scale, a stopwatch, and a physical balance. Name two fundamental quantities you can measure directly with these instruments and two derived quantities you can calculate using them.

Q11. Explain why luminous intensity is considered a fundamental quantity in the SI system, even though it might seem related to energy.

Q12. Classify the following quantities as fundamental or derived: acceleration, temperature, electric charge, pressure, amount of substance, frequency. Give a reason for each classification.

Q13. Explain the concept of fundamental and derived physical quantities with examples. Discuss why the choice of fundamental quantities is somewhat arbitrary and how the SI system standardised these choices.

Q14. Describe how derived quantities are obtained from fundamental quantities. Take the example of "force" and show step-by-step how it is derived from fundamental quantities. Also derive the dimensional formula for force.

Q15. A student argues: "Since all derived quantities can be expressed in terms of fundamental quantities, we don't really need derived quantities at all. We could just use fundamental quantities for everything." Evaluate this argument critically, discussing the practical and conceptual importance of derived quantities in physics.

Q16. A student measures the length of a classroom as 8 m, the breadth as 6 m, and the height as 3.5 m.

(a) Identify which of these measurements represent fundamental quantities and which represent derived quantities.

(b) Calculate the volume of the classroom and express it in SI units.

(c) If 25 students are sitting in the classroom, calculate the average volume of air available per student.

(d) Which fundamental quantities were used to obtain the derived quantity "volume"?

Q17. In a school experiment, a student measures the mass of a wooden block as 250 g, its length as 10 cm, its breadth as 5 cm, and its height as 2 cm.

(a) Calculate the density of the block in kg/m³.

(b) Identify the fundamental quantities involved in the calculation of density.

(c) If the student is told that density is a derived quantity, explain how it is derived from fundamental quantities.

(d) The student now wants to calculate the weight of the block. What additional fundamental quantity is needed, and how is weight derived?

Q18. A physics teacher asks students to prepare a "Fundamental Quantities Chart" for the classroom wall. The chart must include:

(a) The seven fundamental quantities with their SI units and symbols

(b) Five derived quantities commonly used in Class 11 physics, showing how each is derived from fundamental quantities

(c) One example of a quantity that is sometimes treated as fundamental in one system but derived in another

Design this chart in a structured format suitable for display. (Present your answer as a well-organised table or list.)