Mechanics Park Seung-chan Department of Naval Architecture & Ocean Engineering Pusan National University September 11, 2018 Park Seung-chan

1. Concept of mechanics Mechanics Mechanics, an area of physics, is a natural science that explains and predicts the external force to stop or move the object.

2. History of mechanics History From prehistoric times, human beings have already used simple machines such as bevels, wheels, levers and pulley as tools.

2. History of mechanics Archimedes’s spiral water pump A water pump designed by Archimedes in ancient Greece. When the shaft is turned, the spiral connected to the shaft raises the water. <Archimedes’s spiral water pump >

2. History of mechanics Ibn al-Haytham(965 ~ 1040) Development of experimental control methods Creative method of using tool → Knowledge of nature order Al-Haytham’s “position paper” → The dynamics and kinematics theory of object motion → The concept of al-Haytham’s inertia has not been confirmed experimentally

2. History of mechanics Galileo Galilei(1564 ~ 1642) Based his scientific hypotheses on observation and experimentatin. Conclusively refuted Aristotelian ideology Proposed the Law of Inertia, which later became known as Newton’s 1st law of Motion Predict the motion of an object using a mathematical model “All truths are easy to understand once they are discovered; the point is to descover them.” -Galileo Galilei-

2. History of mechanics Isaac Newton (1642 ~ 1727) Classical mechanics Establish classical mechanics Classical mechanics (=Newton’s mechanics) → Physics that explains the relationship between force and motion acting on an onject → Static + Dynamics The starting point of Newton’s mechanics is Kepler’s planetary motion Newton’s law of motion 1st law : The law of inertia 2nd law : The law of acceleration 3rd law : The law of action reaction “If I have seen further than others, it is by standing upon the shoulders of giants” -Isaac Newton-

2. History of mechanics Albert Einstein (1879 ~ 1955) Relativity theory Physics theory on time and space Special Relativity + General relativity The theory that natural laws are invariant to inertial systems and that time and space are relative to observers “It’s not that I’m so smart, It’s just that I stay with problems loger.” -Albert Einstein-

“Science can’t solve the ultimate mystery of nature. 2. History of mechanics Max Planck (1858 ~ 1947) Quantum mechanics quantum mechanics that deals with the shape of a microscopic system Quantum mechanics generalizes classical theory, including all mechanics and electromagnetism The theory that natural laws are invariant to inertial systems and that time and space are relative to observers “Science can’t solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve” -Max Planck-

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