Verified Solution • 2025–26 Session moderate

QJEEM22Phe81c: JEE Main 2022 Physics - Class 11 JEEM22Phe81c Solution: A lead bullet penetrates into a solid object and melts.…

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 ∘^\circ C, Melting point of the bullet = 327 ∘^\circ C, Latent heat of fusion of lead = 2.5 ×\times 104 J kg −- 1, Specific heat capacity of lead = 125 J/kg K)

Multiple Choice Options

  • A 125 ms −- 1
  • B 500 ms −- 1
  • C 250 ms −- 1
  • D 600 ms −- 1

Step-by-Step Verified Solution

25×12mv2=mL+msΔT{2 \over 5} \times {1 \over 2}m{v^2} = mL + ms\Delta T

⇒v25=2.5×104+125+200\Rightarrow {{{v^2}} \over 5} = 2.5 \times {10^4} + 125 + 200

⇒v25=5×104\Rightarrow {{{v^2}} \over 5} = 5 \times {10^4}

⇒v=500\Rightarrow v = 500 m/s

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