1. The planet mars hass a mass of 6.42x10^23kg and a radius of 3396km. What escape speed is needed for a space ship leaving the surface of Mars?
2. To help keep his barn warm on cold days, a farmer stores 950kg of solar-heated water ( Cw= 4186 J/kg C, Lf= 3.33x10^5 J/kg) in barrels. How much heat does the water give off as it cools from 30.0 to 0.0 C and freezes completely?