Final answer:
A pound of iron and a pound of feathers both weigh the same because a pound is a unit of weight, and weight is the measure of gravitational force on a mass. While the density of iron is greater than that of feathers, which affects how much space they take up, it does not change their weight. Thus, both a pound of iron and a pound of feathers have equivalent weight.
Step-by-step explanation:
When comparing a pound of iron and a pound of feathers, the key fact to consider is that a pound is a measure of weight. Therefore, regardless of the material, a pound of any substance will weigh the same. In the context of the old riddle about what weighs more, a ton of feathers or a ton of bricks, they weigh the same because a ton is a standard measure of weight. It's the density of the materials that is different: bricks have a higher density and would take up less volume than feathers to make up the same weight.
Understanding Mass and Weight
It's important to distinguish between mass and weight. Mass is an intrinsic characteristic that describes the amount of matter in an object and is consistent regardless of location. However, weight is the force of gravity acting on an object's mass, which can vary depending on the gravitational pull where the object is measured.
In essence, both a pound of iron and a pound of feathers weigh the same on the Earth's surface because they both represent the same amount of gravitational force acting on the mass.