Integrated SequencePhysics Chemistry Organic Biology

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HyperPhysics - Kinetic Energy

HyperPhysics - Work-Energy Principle

PY105 Notes - Work and Energy
Well-written insightful lecture notes, good at conveying an intuitive feel for the basics of mechanical work and energy.

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Special points of emphasis


Newton's Laws

Work, Energy, and Power

Now we are moving into Discussions arising from Work & Energy. Take a moment to make sure you have achieved your learning goals for this topic. You will find these in the syllabus.

Firstly, let's talk about problem solving. Many problems involving changing speed can be fruitfully approached via either the concepts of Dynamics or Work and Energy.

With the application of force, the object's motion can be analyzed by looking at the change in the state of motion (velocity) over time (dynamics) or it can be analyzed by looking at the change in the state of motion (kinetic energy) through the application of force over distance (work).

If you find yourself stuck trying to solve a problem with reasoning from Newton's Laws or Momentum & Impulse, take a step back and think about the problem in terms of Work & Energy. Often the solution will immediately become clear.

The inclined plane is a classic example. Often the first instinct is to find the acceleration down the plane to determine the final speed, when a simple approach using work & energy may be much faster. No method is always best, so if you get stuck using Dynamics, step back and thing about Work & Energy.

Work, Energy, and Power


The Ideal Gas and Kinetic Theory


As we take a moment to discuss Kinetic Energy in the context of chemical energy, we are embarking on one of the major themes of the first part of this MCAT Course. There will probably be times over the next few months when you may hector me in your imagination. 'Will this view of Chemical Thermodynamics really be on the MCAT?' My answer is that not only will it help you 'on the MCAT' in a direct way for two or three questions (those questions will seem like child's play), but, also, you will find it helps you 'above' the MCAT and 'underneath' it. You are working on a conceptual foundation that will not only make the physical sciences more coherent, but also the biological sciences. Intuitive, conceptual fluency is the only way to a truly superior score on the MCAT.

One of the main themes of the first part of this MCAT course will be to develop our idea of the internal energy of chemical substances using the fundamental tools of Mechanics and basic Electricity & Magnetism. We will return to this theme from many directions. Classical physics is extremely helpful to the conceptual understanding of chemistry, but you must always bear in mind the conceptual departures of quantum mechanics as a corrective. We will devote a great deal of effort to developing the ability to conceptualize chemical change in terms of the main forms of energy within substances at the particle level. As substances undergo chemical transformation, what is happening to energy at the particle level?

The two main forms of energy that are involved in chemical transformations are the electrostatic potential energy among the particles and kinetic energy. In fact, for an ideal gas, translational kinetic energy of the particles is the only form of internal energy. Translational kinetic energy is kinetic energy of a particle whose center of mass is moving through space. The particles of real substances, though, can be bound along lines of chemical bonding and intermolecular force, which do not exist in an ideal gas, so kinetic energy can also exist in most real substances as rotational kinetic energy and vibrational kinetic energy in addition to translational kinetic energy. Furthermore, electrostatic force interactions enable real substances to store energy in the form of electrostatic potential energy. When opposite charges move apart in a chemical transformation or like charges move together, electrostatic potential energy increases.

The WikiPremed MCAT Course is a free comprehensive course in the undergraduate level general sciences. Undergraduate level physics, chemistry, organic chemistry and biology are presented by this course as a unified whole within a spiraling curriculum.

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