5. A gallon of water weighs about 8.3 pounds. A cubic foot of water weighs about 62 pounds. How many gallons of water (to one decimal place) would fill a cubic foot container? 6. The density of a substance is the ratio of its mass to its volume: mass volume Density= Density is usually expressed in terms of grams per cubic centimeter (g/cm). For example, the density of copper is 8.94 g/cm. a. A chunk of oak firewood weighs about 2.85 kg and has a volume of 4100 cm. Determine the density of oak in g/cm. Round to the nearest thousandth. b. A piece of iron weighs 45 ounces and has a volume of 10 in'. Determine the density of iron in g/cm, rounding to the nearest tenth.