Mass is a fundamental property of matter. It remains the same regardless of shape or location. For instance, you will weigh less on the moon than on Earth, but your body’s mass will stay the same.
The metric system, developed by Gabriel Mouton, is now used worldwide. Its basic units are the meter and kilogram.
Gravitational force
Gravity is the force that attracts all objects with mass and pulls them toward each other. Its strength depends on the mass of the objects and their distance apart. The strength of the gravitational force decreases as the distance between the objects increases.
Physicists have long sought to measure the strength of gravity at extremely small masses. Their challenge was to design a detector that would be exquisitely sensitive to the tiny gravitational force between two gold spheres the size of a sesame seed and weighing as much as four grains of rice—the smallest masses for which gravitation has been measured to date.
Gravimeters are instruments used in geology/geophysics to detect small changes in gravity that can reveal information about ocean circulation, glacial melt, droughts or geodesy. Gravimeters are built almost identically to spring balances, except they include a quartz crystal and vacuum chamber. They are also capable of measuring the effects of air resistance on the force of gravity.
Inertia
Inertia is a fundamental property of matter that quantifies the object’s resistance to changes in its state of motion. The more an object has mass, the greater its inertia will be. This inertia is based on Newton’s first law of motion, which states that an object at rest will remain at rest or continue moving at a constant velocity unless acted upon by a net external force.
If an object has a low inertia, it will be easy to change its motion. For example, a large car will resist changing its speed, but a feather lying on a table will change its speed effortlessly.
An object’s inertia can be measured using a balance or a spring scale, which takes g into account. This is how a scientist determines an astronaut’s weight in space by measuring the oscillation of the spring scale with the astronaut attached. This method is known as the “Newton’s cradle”. The inertial mass of an object is proportional to its acceleration.
Density
Density is a physical property that determines how tightly matter is packed together. It is a measurement of the mass of a substance divided by its volume, and it is often used to categorize substances. It is calculated using a formula, and the units are kg over cubic metres. The principle of density was discovered by the Greek scientist Archimedes.
Density explains why a heavier block of lead is denser than a block of Styrofoam, and why large metal ships can float. It also explains why water is denser than air and how oil and vinegar separate into layers.
Knowing how to calculate density is important because it can be used to find the mass of an object based on its volume, or vice versa. It is also useful in determining the composition of an object and identifying its type. The concept of density is a fundamental part of science and is found in everyday life.
Weight
There is a lot of confusion about the difference between mass and weight. Especially in non-scientific contexts, the words are often used interchangeably. While mass measures how much matter something contains, weight is the force of gravity on an object.
The weight of an object will change if you bring it closer to Earth or farther away. However, its mass will stay the same. This is why scientists use balances to measure mass, because they can be used on any planet.
The International Prototype Kilogram, a cylindrical metal alloy cylinder kept in Paris, is the official international standard for kilograms. A kilogram is one of the seven base units in the International System of Units (SI). It was formerly defined by the evaporation of a certain amount of water, but since there is a lack of reliable ways to evaporate water accurately, the kilogram has been redefined using natural constants, such as the speed of light, the Planck constant and the resonant frequency of the caesium atom.