The particle model is the one that describes any object and its mass, concentrated to a single point where size and shape is not so important to be considered.

The above statement remains true if and only if it satisfies two conditions.

• Compared to size of the object, distance travelled by the object is large in comparison.
• Rotations and internal motions are not considered to be a significant feature.

Importance:

• It is important because complex problems can be simplified and analyzed.
• Includes motion of every single atom.
• Treating an object as small particle, important aspects of the motion can be focused neglecting minor information or details that cannot be observed.

Conclusion:

Hence, the details of particle model are described.

The following are the situations where particle model is appropriate.

• Understanding satellite movement or motion.
• Any object travelling over a long distance indicating displacement and velocity.

Conclusion:

Hence, the two examples for which the particle model is appropriate is given.

The following are the situations where practical model is not appropriate for

• Understanding engine operations.
• How bird flies.
• How human beings walk etc.

Conclusion:

Hence, the two examples for which the particle model is not appropriate is given.