What is mass, weight, and density?

All objects have a mass. Because of the force of attraction on the Earth, an object has a weight. This is the force with which the body – that is, the mass of the body – is attracted. The force of gravity on the Moon is just one-sixth of that on the Earth. A person who weighs 6o kg on the Earth weighs only 10 kg on the Moon. The density of an object is the ‘mass per unit volume, i.e., space occupied by 1 kg of a substance. Because of the difference in their densities 1 kg of iron fits in a small cube, and 1 kg of feathers fills a cupboard completely.