7. When a lead bullet hits a large solid target at high speed, its entire kinetic energy is converted into heat. For simplicity, assume that all that heat is concentrated in the bullet rather than the target. If the bullet's initial temperature is 15C, how fast would it have to move before the collision in order to have 30% of its mass melted after the collision? Lead has a melting temperature 327.3C, a specific heat of 128 J/kg K and latent heat of fusion 24500 J/kg.

1. Why does blowing over hot soup cool the soup? 2. Why are icebergs often surrounded by fog? 3. Suppose a new liquid were discovered that is identical to water in every way except that it has a lower latent heat of fusion. Would it take a longer or shorter time to make ice out of this liquid in your freezer? Why? 4. A great amount of water vapor changes phase to become water in the clouds that form a thunderstorm. Does this release thermal energy or absorb it? Explain. Quantitative Practice 5. Steam at 100 C is added to ice at 0.C. Find the temperature when the mass of steam is 10 g and the mass of ice is 50 g. The specific heat of water is 4186 J/kgoC, its latent heat of fusion is 3.33x105 J/kg and its heat of vaporization is 2.26x10 ]/kg. 6. In an insulated vessel, 250 g of ice at OC is added to 600 g of water at 18.C. How much ice remains when the system reaches equilibrium? Assume the heat of fusion of ice is 79.7 cal/g and its specific heat is 0.5 cal/g.C. The heat of vaporization of water is 540 cal/g and its specific heat is 1 cal/goC