Thermal Properties of Matter
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Question : 12
Total: 22
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 – 1 K – 1
Solution:
Here, P = 10 k W = 10 4 W , m = 8.0 k g = 8 × 10 3 g
rise in temperature,Δ T = ? ,
time,t = 2.5 min
= 2.5 × 60 = 150 s
Sp. heat,c = 0.91 J g − 1 K − 1
Total energy,= P × t = 10 4 × 150
= 15 × 10 5 J
As, 50% of energy is lost,
∴ Δ Q =
× 15 × 10 5
= 7.5 × 10 5 J
AsΔ Q = m c Δ T
∴ Δ T =
=
= 103 ° C
rise in temperature,
time,
Sp. heat,
Total energy,
As, 50% of energy is lost,
As
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