Ncert Exercises & Solutions

11.12: 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 = $0.91 J g^{- 1} K^{- 1}$

It is given in the question that:

Power of the machine, P = 10 kW = 10 × 10 $^{3}$ W

Mass of the block, m = 8.0 kg = 8 × 10 $^{3}$ g

Time, t = 2.5 min = 2.5 × 60 = 150 s

Specific heat of aluminium, c = 0.91 J g $^{- 1}$ K $^{- 1}$

The total energy of the drilling machine = Pt = 10 × 10 $^{3}$ × 150 = 1.5 × 10 $^{6}$ J

$Useful energy = \frac{50}{100} \times 1.5 \times 10^{6} = 7.5 \times 10^{5} J$
$Rise in the temperature of the block after drilling,$
$∴ ∆ T = \frac{∆ Q}{mc} = \frac{7.5 \times 10^{5}}{8 \times 10^{3} \times 0.91} = 103 ° C$

Therefore, the rise in the temperature of the block is 103°C.

NEET Information

courses

Company

Botany Questions

Chemistry Questions

Physics Questions

Zoology Questions