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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 `kcal//kg`. The minimum velocity with which the fragment must have entered the atmosphere is :

A

`"0.45 km s"^(-1)`

B

`"1.32 km s"^(-1)`

C

`"2.32 km s"^(-1)`

D

Zero

Text Solution

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The correct Answer is:
B
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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

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