Verified Solution • 2025–26 Session moderate

QPages 12-14: Q34: HC Verma: Concepts of Physics - Volume 2 Heat and Temperature Pages 12-14: Q34 Solution: A circular disc made of iron is rotated about its axis at a…

⚠️ Common Exam Traps & Conceptual Pitfalls

Students frequently take the fractional change $\Delta v/v = \alpha\Delta T$ and report it as the percent change, forgetting to multiply by 100; this turns a $3.6\times10^{-4}$ change into 0.036% instead of 0.036. Always convert the dimensionless ratio to a percentage by multiplying by 100.

A circular disc made of iron is rotated about its axis at a constant velocity ω\omega. Calculate the percentage change in the linear speed of a particle of the rim as the disc is slowly heated from 20�C to 50�C, keeping the angular velocity constant. Coefficient of linear expansion of iron = 1.2×10−5 �C−11.2 \times 10^{-5} \text{ �C}^{-1}.

Step-by-Step Verified Solution

**Answer:** Percentage change =0.036%= 0.036\% **Step-by-Step Explanation:** Linear speed v=ωrv = \omega r. Since ω\omega is constant, v∝rv \propto r. Δv/v=Δr/r=αΔT=1.2×10−5×30=3.6×10−4=0.036%\Delta v/v = \Delta r/r = \alpha \Delta T = 1.2 \times 10^{-5} \times 30 = 3.6 \times 10^{-4} = 0.036\%.

All Questions in this Chapter

QPage 11: Q1 QPage 11: Q2 QPage 11: Q3 QPage 11: Q4 QPage 11: Q5 QPage 11: Q6 QPage 11: Q7 QPage 11: Q8 QPage 11: Q9 QPage 11: Q10 QPage 11: Q11 QPage 11: Q12 QPage 11: Q13 QPage 12: Q1 QPage 12: Q2 QPage 12: Q3 QPage 12: Q4 QPage 12: Q5 QPage 12: Q6 QPages 11-12: Q1 QPages 11-12: Q2 QPages 11-12: Q3 QPages 11-12: Q4 QPages 11-12: Q5 QPages 11-12: Q6 QPages 11-12: Q7 QPages 11-12: Q8 QPages 11-12: Q9 QPages 11-12: Q10 QPages 11-12: Q11 QPages 12-14: Q1 QPages 12-14: Q2 QPages 12-14: Q3 QPages 12-14: Q4 QPages 12-14: Q5 QPages 12-14: Q6 QPages 12-14: Q7 QPages 12-14: Q8 QPages 12-14: Q9 QPages 12-14: Q10 QPages 12-14: Q11 QPages 12-14: Q12 QPages 12-14: Q13 QPages 12-14: Q14 QPages 12-14: Q15 QPages 12-14: Q16 QPages 12-14: Q17 QPages 12-14: Q18 QPages 12-14: Q19 QPages 12-14: Q20 QPages 12-14: Q21 QPages 12-14: Q22 QPages 12-14: Q23 QPages 12-14: Q24 QPages 12-14: Q25 QPages 12-14: Q26 QPages 12-14: Q27 QPages 12-14: Q28 QPages 12-14: Q29 QPages 12-14: Q30 QPages 12-14: Q31 QPages 12-14: Q32 QPages 12-14: Q33 QPages 12-14: Q34

Related Learning Resources & Exam Preparation

Chapter Practice Bank
Practice all topic-wise questions from Heat and Temperature
Reference Textbook Solutions
Explore complete chapter exercises for HC Verma: Concepts of Physics - Volume 2
Competitive PYQ Question Bank
Browse year-wise authentic previous years' questions with solutions
Authentic CBT Mock Tests
Simulate official exam environment with live timer and percentile scoring