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Mechanics is a field in physics concerned with the statics, dynamics, and kinetics of physical objects and how they behave when we apply forces, torques, etc. In the Expii mechanics track, you will learn about motion, rotation, forces, torques, and more.
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Mechanics is the general study of motion, forces, energy and their inter-relationships. It is usually divided into 3 categories:
Statics is the study of forces in the absence of motion.
Kinematics is the study of motion without regard to forces.
And Dynamics is the study of motion keeping in view the forces present.
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What are mechanics?
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Well, you guessed it! In complicated terms, it is "the branch of science concerned with the behavior of physical bodies when subjected to forces or displacements, and the subsequent effects of the bodies on their environment"
But, all you need to know is that it is the study of how different kinds of motion and forces intertwine to produce motion.
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To motivate the study of mechanics, let's view a video involving a spinning wheel.
In the video, the motion of the wheel does not seem natural. Instead it seems very counter-intuitive. Nevertheless, the motion can be explained using a few simple rules. The example in the video shows that it is necessary to discover and carefully apply these rules in order to accurately predict an object's motion. This is the purpose of mechanics.
Mechanics is the study of the fundamental laws governing motion.
Beyond the bicycle wheel, there are other examples of physical systems that can be studied with mechanics. One of the simplest examples is a ball being dropped and falling to the ground. Another example of is a ball rolling down a ramp. A more exotic example is the motion of planets and galaxies.
Not all physical systems are studied with mechanics. For example, if you put a drop of dye in a cup of water, the dye diffuses until it is completely mixed with the water. However, this diffusive motion of the dye is not usually analyzed at the level of the individual molecules with definite motion. This approach is too difficult because of the large number of molecules present. Instead, a theoretically inexact statistical approach is used. Because diffusion uses this statistical approach instead of studying the exact motion of each individual molecule, the study of diffusion is not considered mechanics.
Another system which is not studied using mechanics is electrical circuits. Again, there are a large number of particles involved, so a different approach is used, where the concepts of "voltage", "current", and "resistance" are introduced to describe the average motion of a large number of particles, instead of focusing on the individual motions of each particle.
Mechanics---the study of motion---can be broken down into two parts. First, a "language" must be developed to describe motion in a precise and unambiguous manner. Second, laws predicting future motion from currently observed motion must be stated. Let's look at both of these in more detail.
The technical name for the first part is kinematics. Kinematics is the description of motion. Kinematics will give us a way to specify precisely where an object is at any point in time and how quickly and in what direction it is moving. Although kinematics has great descriptive power, it has no power to predict: even if we have an exact description of the past motion of an object, and we can describe any future motion in a very precise way, we still don't know which future motion will actually result from the past motion.
The technical name for the second part of mechanics---using past motion to predict future motion---is dynamics. Dynamics is the study of the physical laws governing motion.
