Concepts of Work and Energy in Physics

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Course on Work Energy and Power is for   learners and students preparing for Advance Placement Physics examination and other college level examination . Also students perparing for various engineering and medical entrance examination can also take up couse. Any underage student or learner must take up the course under his/her parent guidance.

Conservation laws play an important role in physics. Such laws assert that some

quantity is conserved, which means that the quantity remains constant even when

particles or bodies suffer drastic changes involving motions, collisions, and reactions.

One familiar example of a conservation law is the conservation of mass. Expressed in

its simplest form, this law asserts that the mass of a given particle remains constant,

regardless of how the particle moves and interacts with other particles or other bodies.

In the preceding two chapters we took this conservation law for granted, and we treated

the particle mass appearing in Newton’s Second Law (ma = F) as a constant, time independent quantity.

More generally, the sum of all the masses of the particles or

bodies in a system remains constant, even when the bodies suffer transformations and

reactions.

This conservation law is one of the most fundamental laws of nature. Although we will derive this law from

Newton’s laws, it is actually much more general than Newton’s laws, and it remains

valid even when we step outside of the realm of Newtonian physics and enter the realm

of relativistic physics or atomic physics, where Newton’s laws fail. No violation of the

law of conservation of energy has ever been discovered.

In mechanics, we can use the conservation law for energy to deduce some features of the

motion of a particle or of a system of particles when it is undesirable or too difficult to calculate the full details of the motion from Newton’s Second Law. This is especially

helpful in those cases where the forces are not known exactly.But before we can deal with energy and its conservation, we must introduce the concept of work. Energy and work are closely related. We will see that the work done by

the net force on a body is equal to the change of the kinetic energy