A piece of plastic barely floats in water. If it has a mass of 20g, what is its volume?
2cm
To determine the volume of the plastic, we need to know its density. The density of an object is defined as the mass of the object divided by its volume.
In this case, we can use the fact that the plastic just barely floats in water to estimate its density. When an object floats in water, it displaces an amount of water equal to its own weight. Since the plastic barely floats, we can assume that the weight of the displaced water is close to its own weight.
The density of water is approximately 1g/cm³. Therefore, if the plastic has a mass of 20g and displaces an equal weight of water, it must have a volume of 20 cm³ (20g / 1g/cm³ = 20 cm³).
So, the volume of the plastic is 20 cm³.