STANDARDPhysics-Thermodynamics
STANDARD Physics Heat Transfer MCQ Question
Type: MCQ-numerical-Medium-Class 11
A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8 kg. Find the rise in temperature of the block in 2.5 minutes, assuming 50% power is used up in heating the machine itself or lost to the surroundings. (Specific heat of aluminium = 0.91 J g⁻¹ °C⁻¹)
A
100°C
B
103°C
C
150°C
D
155°C
Correct Answer
Option B
Detailed Explanation
The total energy used is P × t = 10⁴ × 150 = 15 × 10⁵ J. Since 50% of energy is lost, the energy available for heating is 7.5 × 10⁵ J. Using ΔQ = msΔT, we find ΔT = 103°C.
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