Use the worked example above to help you Suppose a lead bullet with mass $6\mathrm{.}25$ g and an initial temperature of $90\mathrm{.}0$C hits a wall and completely liquefies. What minimum speed did it have before impact? $($Hint: The minimum speed corresponds to the case where all the kinetic energy becomes internal energy of the lead and the final temperature of the lead is at its melting point. Don't neglect any terms here! The specific heat and latent heat of fusion of lead is $128$ J$/$kg $$C and $2\mathrm{.}45104$ J$/$kg$,$ respectively. The melting point of lead is $327\mathrm{.}3$C$.)$

m$/$ssolve this problem. A comet half a kilometer in radius consisting of ice at $273$ K hits Earth at a speed of $2\mathrm{.}01104$ m$/$s$.$ For simplicity, assume that all kinetic energy converts to thermal energy on impact and that all the thermal energy goes into warming the comet.

$($a$)$ Calculate the volume and mass of the ice.

Volume m$3$Mass kg

$($b$)$ Use the conservation of energy to find the final temperature of the comet material. Assume, contrary to fact, that the result is superheated steam and that the usual specific heats are valid, though in fact they depend on both temperature and pressure.

K