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Q10.12: NCERT Physics - Part 2 THERMAL PROPERTIES OF MATTER 10.12 Solution: A 10 kW drilling machine is used to drill a bore in a small…

⚠️ Common Exam Traps & Conceptual Pitfalls

Specific heat is given as $0.91 mathrm{J,g^{-1},K^{-1}}$, so it must be converted to $910 mathrm{J,kg^{-1},K^{-1}}$ before using the mass in kilograms. Using $0.91$ directly with $m=8.0 mathrm{kg}$ would underestimate the heat capacity by a factor of 1000 and give a wildly incorrect temperature rise.

A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminium = 0.91 J g__ K__.

Step-by-Step Verified Solution

**Answer:** Rise in temperature = 103 �C **Step-by-Step Explanation:** Useful power = 50% of 10 kW = 5000 W. Energy supplied in 2.5 minutes = 5000×2.5×60=7.5×1055000 \times 2.5 \times 60 = 7.5 \times 10^5 J. Using Q=mcΔTQ = mc\Delta T:
ΔT=Qmc=7.5×1058.0×0.91×103=7.5×1057280=103∘C\Delta T = \frac{Q}{mc} = \frac{7.5 \times 10^5}{8.0 \times 0.91 \times 10^3} = \frac{7.5 \times 10^5}{7280} = 103^\circ\text{C}
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All Questions in this Chapter

Q10.1 Q10.2 Q10.3 Q10.4 Q10.5 Q10.6 Q10.7 Q10.8 Q10.9 Q10.10 Q10.11 Q10.12 Q10.13 Q10.14 Q10.15 Q10.16 Q10.17 Q10.18 Q10.19 Q10.20

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