A lead bullet at $27°C$ just melts when stopped by an obstacle. Assuming that $25\%$ of heat is absorbed by the obstacle, then the velocity of the bullet at the time of striking........ $m/sec$  ($M.P.$ of lead $= 327°C,$ specific heat of lead $= 0.03\, cal/gm°C,$ latent heat of fusion of lead $= 6\, cal/gm$ and $J = 4.2\, joule/cal)$

  • [IIT 1981]
  • A

    $410$

  • B

    $1230$

  • C

    $307.5$

  • D

    None of the above

Similar Questions

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$(a)$ At what temperature and pressure can the solid, liquid and vapour phases of $CO _{2}$ co-exist in equilibrium?

$(b)$ What is the effect of decrease of pressure on the fusion and boiling point of $CO _{2} ?$

$(c)$ What are the critical temperature and pressure for $CO _{2} ?$ What is their sıgnificance ?

$(d)$ Is $CO _{2}$ solid, liquid or gas at $(a)\;-70\,^{\circ} C$ under $1\; atm$, $( b )\;-60\,^{\circ} C$ under $10 \;atm,$ $(c)$ $15\,^{\circ} C$ under $56$ atm ?

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A metallic ball and highly stretched spring are made of the same material and have the same mass. They are heated so that they melt, the latent heat required

  • [AIIMS 2002]

Two substances $A$ and $B$ of equal mass m are heated at uniform rate of $6\, cal s^{-1}$ under similar conditions. $A$ graph between temperature and time is shown in figure. Ratio of heat absorbed ${H_A}/{H_B}$ by them for complete fusion is