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An iron rocket fragment initially at -10...

An iron rocket fragment initially at `-100^@C` enters the earth's atmosphere almost horizontally and quickly fuses completely in atmospheric friction. Specific heat of iron is `0.11 kcal//kg^@C`. Its melting point is `1535^@C` and the latent heat of fusion is `30 kcals//kg`. The minimum velocity with which the fragmento must have entered the atmosphere is

A

0.45 km/s

B

1.32 km/s

C

2.32 km/s

D

Zero

Text Solution

Verified by Experts

The correct Answer is:
B
Loss in in KE = Gain in heat energy
`(1)/(2)mV^(2)=[m(30)+m(0.11)(1535^(@)C-(-100^(@)C)]4184`
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