To describe: The particle model.

The details of particle model are described.

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.

To give: The two examples for which the particle model is appropriate.

The two examples for which the particle model is appropriate is given.

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.

To give: The two examples for which the particle model is not appropriate.

The two examples for which the particle model is not 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.