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A lead bullet penetrates into a solid object and melts. Assuming that 40% of its kinetic energy is used to heat it, the initial speed of bullet is: (Given initial temperature of the bullet = 127°C), Melting point of the bullet = 327°C, Latent heat of fusion of lead = 2.5 × 10 4 J kg –1 Specific heat capacity of lead = 125 J/kg K)

1. 125 ms –1
2. 500ms –1
3. 250ms –1
4. 600ms –1

Correct answer: 500ms –1

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