Physics has an important role in our life. Without physics and the work of physicists, our modern life would not exist. Using physics, people created machines, instruments and some different divices from the crudest to the most modern aspect. Techology is developed more rapidly, more modern day by day. Moreover, all other natural sciences- example chemistry, biology, medicinedepend upon physics for the foundations of their knowledge. Physics holds this key position because it is concerned with the most fundamental aspect of matter and energy and how they interact to make the physical universe. Physics has some main problems: mechanics, electricity and magnitism, heat, wave and sound, optics, nuclear physics,. | Physics Physics has an important role in our life. Without physics and the work of physicists our modern life would not exist. Using physics people created machines instruments and some different divices from the crudest to the most modern aspect. Techology is developed more rapidly more modern day by day. Moreover all other natural sciences- example chemistry biology medicine-depend upon physics for the foundations of their knowledge. Physics holds this key position because it is concerned with the most fundamental aspect of matter and energy and how they interact to make the physical universe. Physics has some main problems mechanics electricity and magnitism heat wave and sound optics nuclear physics atomic particles. CHAPTER 1 MECHANICS Mechanics is a branch of physics concerned with the behavior of physical bodies under the effect of the bodies on their enviroment. The early modern period scientists such as Galileo Kepler and especially Issac Newton laid the foundation for a field of mechanics and now it is known as classical mechanics or Newtonian mechanics. Mechanics has two major divisions classical and quantum mechanics. Classical mechanics came first while quantum mechanics did not appear until 1900. Both commonly constitute the most certain knowledge that exists about physical nature. Classical mechanics is concerned with the physical laws governing the motions of bodies. It is used for describing the motion of marcroscopic objects such as parts of machinery astronomical objects inclue spacecraft planets stars galaxies. It is one of the oldest and lagest subjects in science engineering and technology. Classical mechanics is divided into statics dynamics and kinematics. Statics studies matter at rest or in motion with constant velocity. It deals with the balancing of forces with approriate resistance to keep matter at rest. It is commonly used for designing buildings and bridges. Different from statics dynamics studies matter in motion example motion of .