Kids are naturally curious, so it’s important to fuel that desire for knowledge by teaching them the basics of the metric system early. This includes the basic units of length, mass, and volume.

Mass is an inertial property of matter and varies only with the type of atoms it contains. Weight, on the other hand, depends on the gravitational force exerted on the object.

Kinetic energy

Kinetic energy is the energy of motion, and every object or particle that moves has kinetic energy. This energy is not the same as, or even a part of, the object’s mass.

It is measured in units called joules, derived from the metre-kilogram-second system of measurement and defined as the product of an object’s mass times its velocity squared. For objects in low to medium speeds, this formula is generally accurate enough.

However, macroscopic bodies may possess other internal energies at the molecular or atomic level that cannot be described by kinetic energy alone, such as vibrational, rotational and electromagnetic energy. These energies contribute to a body’s mass and inertia. Such internal energies are considered part of a body’s total energy under the Law of Conservation of Energy.

Gravity

Gravity is the force that holds the planets in orbit, pulls ocean water up into tides and keeps stars and even black holes together. It is one of four fundamental forces that govern all matter and energy in our universe, but it is the least understood of the four.

Unlike electricity and magnetism, which can attract or repel, gravity is a universal force that always pulls. That is why physicists must design incredibly sensitive equipment to measure it.

To accurately measure gravity, a special device known as a gravimeter is required. These instruments are similar to accelerometers, but designed with extreme precision and stability. This is because they must be able to ignore vibrations and other environmental influences on their measurement. They are often used for calibration of relative instruments or in geophysical studies.

Weight

Mass is one of the basic properties of matter. It doesn’t change, regardless of shape or location, although it does change if energy is given or taken from the object.

Weight, on the other hand, changes based on the force of gravity on an object. It can be zero in a no-gravity environment, such as space.

To measure mass, a balance is used to place the object under test on one pan and standard masses are placed on another pan. Each standard mass is added one at a time until the pointers on both pans balance. This is done until the object under test has been weighed to the nearest kilogram (kg). It may also be measured with a triple beam balance, lever balance or an electronic balance.

Balance

A balance is used to determine an object’s mass by comparing it to another known quantity. This is the same process that a common bathroom scale uses to obtain a person’s weight. Modern digital scientific balances use a different method, but they still operate by comparing objects.

Daily inspections of mechanical and electronic balances include checking for sensitivity error. This component of error depends on the state of the balance and its original performance level.

To minimize this error, make sure that only clean, dry objects are placed on the weighing pan. Also, close the balance door during weighing to prevent air currents from disturbing the reading. This is especially important for analytical balances that have closed models with tare functions, limit function for check weighing, and unit-of-measure conversion.

Transducers

A transducer is a sensor that converts the change in measurand into a usable output energy. It can produce mechanical output or electrical signal or both. For example, a bimetallic strip in a thermocouple responds to changes in temperature by changing its own internal resistance. Its response is converted to an output pulse.

A force restoration instrument is used in the mass measurement of heavy objects. These devices use piezoelectric transducers to transform mechanical stress into a proportional electrical signal that can be measured by an electronic circuit.

The first method of classification is based on the physical quantity changed into an electrical signal that includes displacement, force, pressure, & strain. This can be further divided into passive & active transducers. The second method of classification is based on the structure otherwise the phenomena of their working like in the case of a microphone or loudspeaker.