Question 282: Thermodynamics & KTG

Question

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 $$	imes$$ 10
4
J kg
$$-$$1
, Specific heat capacity of lead = 125 J/kg K)

Accepted Answer

$${2 \over 5} 	imes {1 \over 2}m{v^2} = mL + ms\Delta T$$
$$ \Rightarrow {{{v^2}} \over 5} = 2.5 	imes {10^4} + 125 + 200$$
$$ \Rightarrow {{{v^2}} \over 5} = 5 	imes {10^4}$$
$$ \Rightarrow v = 500$$ m/s

Answer

125 ms
$$-$$1

Answer

500 ms
$$-$$1

Answer

250 ms
$$-$$1

Answer

600 ms
$$-$$1

Thermodynamics & KTG

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