Question

A drilling machine of 5 kW is used to drill a hole in the block of copper of mass 4 kg . Calculate the rişe in temperature of the block in 5 minutes.if \( 75 \% \) of the energy is used in heating the block. Given specific heat of copper \( =0.385 J g -1^{\circ} C - I \),

Answer 1

Total Energy Supplied:

Power: 5 kW = 5000 W
Time: 5 minutes = 5 × 60 = 300 seconds
Total Energy Supplied:

Total Energy = Power × Time

Total Energy = 5000 W × 300 seconds = 1,500,000 J

 Energy Used for Heating:

Efficiency: 75% = 0.75
Energy Used for Heating:

Energy = Total Energy × Efficiency

Energy = 1,500,000 J × 0.75 = 1,125,000 J

Temperature Rise:

• Mass of Copper: 4.0 kg = 4000 g
• Specific Heat of Copper: 0.385 J/g°C
• Formula: ΔT = Energy Used / (Mass × Specific Heat)

Substituting the values:

ΔT = 1,125,000 J / (4000 g × 0.385 J/g°C)

ΔT = 1,125,000 J / 1540 J/°C

ΔT ≈ 730.52°C