Particle

The word particle sometimes refers to the pollution type: particulate matter.

Figure 1. Elastic potential energy stored by a spring.

A particle is an object that is treated as if it has no internal structure. Particles can be treated as point masses. A point mass is a dimensionless object with mass or an object with a single position. Treating objects as particles makes it easier to demonstrate how forces act on the object. This approximation also makes calculating kinetic energy and potential energy easier. Objects can not be treated as a particle if their structure is important. For example, as seen in Figure 1, the spring has elastic potential energy associated with deformation: so it can not be treated as a particle because its internal structure matters. Objects that have structure that can be ignored, like a ball being thrown, can be treated as a particle.

Particulate matter is often treated as a collection of particles because of the importance of its size and mass. Specific shape, colour, and chemical makeup are often overlooked. Most often, particulate matter is only a few microns across. Particles can be much smaller. Photons and electrons are sometimes considered particles. While this is true, they can also considered waves. This is one of the strange results of quantum mechanics. To learn more about particle-wave duality, please see hyperphysics.

Figure 2. A pitcher exerts a force on a baseball which can be treated as a particle because the internal structure can usually be ignored.

For Further Reading

For further information please see the related pages below:

• Quantum mechanics
• Atom
• Electron
• Proton
• Or explore a random page