Physics homework question...?

Question

A 0.003 kg lead bullet is travelling at a speed of 240 m/s when it embeds in a block of ice at 0 degrees celsius. If all the heat generated goes into melting ice, what quantity of ice is melted? (Lf of water = 3.33 x 10^5 J/kg, specific heat of lead = 128 J/kg degrees celsius)

i know its complicated but if you can give me any start to this problem, i would very much appreciate it. thanks :)

Answer 1

Before we apply the law of conservation energy, lets find out all the energy existed in the system, before and after the collision.

Before,

Kinetic energy of the lead bullet = 0.5mv^2

=0.5(0.003)(240)^2=86.4J

The excess heat energy stored in the bullet compared to 0 degree celcius bullet = 0.003(128) = 0.384 J

After

Kinetic energy of the bullet = 0 (since it is stopped)

The heat used to melt the ice = m(Lf), m is the mass of ice melted.

Hence, we can apply the law now which is

86.4 + 0.384 = m(Lf)

Thus, m = 86.784/(3.33x10^5) =0.000261kg

=0.261g #