# How to find the mass , knowing the amount of : piggy knowledge

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weight and volume are inseparable values are closely dependent each other.If you increase the volume of the substance, and will increase its mass, and similarly in the reverse order.In real life it is often necessary to calculate the weight or volume of a body or product.In this article, we consider the simplest examples, and see exactly how to find the weight of knowing the volume and vice versa.

remember the old children's riddle: "What is heavier than a kilogram of lint or a kilo of iron?".A "same weight" on the surface, however, most responsible "iron".The reason is that the iron has a higher density.Density - a constant value, which is calculated as the ratio of body mass to its volume.And if the volume of a kilogram takes down at least one big pillow, the iron is enough volume three matchboxes.

simple example: how to find the mass of water contained in a two-liter bottle?The answer is simple

: the body must be multiplied by the volume density of the body.Density of substances and materials scientists have long been calculated, their values can be found in special tables densities.But for water, this value is the reference and catchy equal to 1 gram per cubic centimeter, or 1 kilogram per cubic decimeter equivalent liter.So, how to transfer the amount in weight?Multiply the density of water (1 kg / liter) on its volume (2 liters): 1 * 2 = 2 kg.General view of the formula: m = p * V, where m - the mass of the body, p - the density, V - volume.Using this formula, you can solve the inverse problem.Expressing the volume of the mass and density, to learn that V = m / p.For example, a full bottle of pure water has a mass of 7 kg, calculate its volume.Solution 7 (kg) / 1 (kg / liter) = 7 liters.

To calculate the density of non-homogeneous mixtures there are methods how to calculate the molar mass of the substance or the average density.For example, the weight of the mixture find a pint of water and half a liter of mercury.Mercury density is 13 kg / liter, the weight of half a liter is equal to: 13 * 0.5 = 6.5 kg.Half a liter of water has a mass of 0.5 kg.In sum, the weight of the mixture is equal to 7 kg and occupies a volume of one liter.Consequently, the density of the mixture to 7 kg / liter.

Knowing how to find the mass of the density, you can find the weight of gases and cosmic bodies.Interestingly, the average density of air under normal conditions is equal to 1.5 kilograms per cubic meter.The volume of the earth's atmosphere is approximately 1.4 * 10 ^ 18 cubic meters (fourteen to seventeen zeros).So the mass of the whole air of the planet is 1.5 * 1.4 * 10 ^ 18 = 1.1 * 10 ^ 18 kilograms degree.This is a huge quantity equal to the weight of the train length from the Earth to Mars.