Perhaps it is obvious, but I think it was probably negligent of me to assume that the reason for studying mechanics needed no explanation. If an aircraft flies through a hailstorm, then in advance the passengers and crew would like to know that it will survive the event, and after the event the owners and operators would to know whether it can continue to be flown safely. Mechanics is the core discipline or field that underpins such knowledge. It is concerned with the way materials and, or structures (e.g. the aircraft skin) behave when acted upon by a load (impact by hail stones).
Since everything involved in this examples is solid, this type of analysis is usually called solid mechanics. Whereas predicting the lift and drag on the aircraft wings as they are pushed through the air by the engines is classified as fluid mechanics.
Everyday examples of both solid mechanics and fluid mechanics have been collected together to assist in introducing engineering students to these fields and can be found at http://www.EngineeringExamples.org and http://www.EngageEngineering.org