Classic Mechanics is a sub-area of Mechanics dedicated to the study of the movements of bodies on Earth and immersed in fluids below the speed of light and the causes of these movements. Classical Mechanics is mainly divided into the areas of Kinematics, Dynamics, Statics, Hydrostatics and Hydrodynamics. The study of Classical Mechanics is of great importance for a huge range of professions, in addition to being the most demanded Physics content in the National High School Examination (Enem).
Read too: Modern Physics — the field of Physics that emerged to explain some concepts that Classical Mechanics could not explain
Topics of this article
- 1 - Summary of Classical Mechanics
- 2 - What does Classical Mechanics study?
-
3 - Main areas of study of Classical Mechanics
- → Kinematics
- → Dynamics
- → Static
- → Hydrostatic
- → Hydrodynamics
- 4 - Importance of Classical Mechanics
- 5 - Classic Mechanics in Enem
- 6 - What are the main areas of study in Mechanics?
Abstract on Classical Mechanics
Classical Mechanics is a subfield of Mechanics, one of the main areas of Physics.
She studies the movements of bodies on Earth and immersed in fluids below the speed of light and the causes of these movements.
The main areas of study of Classical Mechanics are Kinematics, Dynamics, Statics, Hydrostatics and Hydrodynamics.
Kinematics studies the situations that occur from the moment a body starts its state of motion.
Dynamics studies the causes that gave rise to some movement.
Statics studies the conditions of equilibrium in extended bodies.
Hydrostatics studies fluids under conditions of static equilibrium.
Hydrodynamics studies fluids in motion when subjected to non-zero external forces.
The three main areas of Mechanics are Classical Mechanics, Quantum Mechanics and Relativistic Mechanics.
Classical Mechanics is the Physics content that falls most in the Enem.
What does Classical Mechanics study?
Classical Mechanics studies the movements of bodies on Earth and immersed in fluids below the speed of light, in addition to the causes of these movements. It is usually divided into Kinematics, Dynamics, Statics, Hydrostatics and Hydrodynamics.
Main areas of study of Classical Mechanics
→ Kinematics
Kinematics is the area of Classical Mechanics that studies the motion of bodies without taking into account the causes of this motion. In other words, situations that occur from the moment a body starts its state of motion are studied. Within the scope of Kinematics, which is seen in high school, the types of movement that we will see below are studied.
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◦ Uniform motion (MU)
Uniform motion is the motion where the velocity of a body is constant, moving only in a straight line. The main equation used for the study of uniform motion is the hourly function of position.
Position time function for the MU:
\(S_F =S_0 + vt\ or\ v= \frac{ΔS}{Δt}\)
◦ Uniformly Varied Motion (MUV)
Uniformly varied motion is the motion where the velocity of a body changes at constant rates. In the case where the movement has its speed increased, we say it is an accelerated movement; if the speed decreases, we say it is a retarded movement.
The most important equations for describing uniformly varied motion are the hourly functions of position and velocity and Torricelli's equation.
Position time function for the MUV:
\(S_F =S_0 + v_0 t+\frac{at^2}2\ or\ \triangle S=v_0 t+ \frac{at^2}2,\ com\ \triangle S =S_F -S_0 \)
Velocity hourly function for the MUV:
\(V_F =V_0 + at\)
or
\( a= \frac{V_F- V_0}{t_F-t_0}\)
Torricelli's Equation:
\(V_F ^2 =V_0 ^2 + 2a\triangle S\)
◦ Uniform circular motion (MCU)
Uniform circular motion is the motion in which the direction of velocity of a moving object is constantly changing so that its distance from a point in space remains constant. Even if called uniform circular motion, this motion is accelerated, since in order to describe a circular trajectory, the existence of a centripetal acceleration is necessary.
In the study of circular motion, we are faced with a large number of equations, and there are: equations that calculate displacement and scalar velocity; equations that calculate angular quantities, such as angular velocity; and, finally, equations that serve to relate these two types of quantities. Check out some of the most important equations of circular motion.
Angular velocity for the MCU:
\(ω = \frac{Δθ}{Δt}\)
or
\(ω = 2πf\)
or
\(ω = \frac{2π}T\)
Relationship between speed and angular speed:
\(V = ωR\)
Frequency and period:
\(f = \frac{1}T\)
\(T = \frac{1}f\)
◦ Uniformly Varied Circular Motion (MCUV)
Uniformly varied circular motion is the motion which is a slightly more general case of uniform circular motion. In it, in addition to a centripetal acceleration, there are constant angular and tangential accelerations, which cause the angular velocity of the mobile to vary uniformly. As we do in uniformly varied motion, in the study of the MCUV we use very similar position and velocity hourly functions.
Clockwise function of the angular position of the MCUV:
\(θ_F =θ_0 + ω_0 t+\frac{at^2}2\)
Hourly function of the angular velocity of the MCUV:
\(ω_F = ω_0 = at \)
See too:Techniques for solving Kinematics exercises
→ Dynamics
Dynamics is the area of Classical Mechanics that studies the causes that gave rise to some movement. In this sense, we study the forces that act on a body, the quantities of movement, the energy mechanics, impulse and magnitudes related to rotational movements, such as torque and moment angular.
The foundations of the study of dynamics in high school are the newton's three laws. Based on them, the other equations of the subarea and also of Kinematics are derived. Check out some of the most important formulas used in the study of Dynamics:
Newton's second law:
\(F=m\cdot a\)
Torque or moment of a force:
\(T=Fdsenθ\)
Linear momentum or linear momentum:
\(Q=mv\)
Angular Momentum or Angular Momentum:
\(L=rQsenθ\)
Kinetic energy:
\(E_c=\frac{mv^2}2\)
→ static
Statics is the area of Classical Mechanics that studies the equilibrium conditions in extended bodies, that is, it determines what measures or even the intensity of forces and torques should be so that a body of non-negligible dimensions can remain in equilibrium. In the study of statics, Newton's laws are widely used.
→ hydrostatic
The Hydrostatic is the area of Classical Mechanics that studies fluids under conditions of static equilibrium. In it, we studied specific mass, pressure, Stevin's principle, Pascal's theorem and Archimedes' theorem.
→ Hydrodynamics
Hydrodynamics is the area of Classical Mechanics that studies fluids in motion when subjected to non-zero external forces. In it, we study flow, continuity equation and Bernoulli's principle.
Importance of Classical Mechanics
Classical Mechanics has great importance in several aspects. Below, we highlight some understandings that were only possible through research in Classical Mechanics:
The orbits of planets, satellites and asteroids, described by the law of universal gravitation It is by Kepler's laws.
The trajectory of rockets, bullets, darts and arrows explained using projectile launch equations.
The flow of fluids, described by the equation of continuity, capable of explaining the flight of airplanes, as well as the hydrostatic situations, in which the fluids are at rest.
The operation of simple machines, such as inclined planes, pulleys, hoists, scales, etc.
The trajectory of electrically charged particles moving under the action of electric and magnetic fields, as in the aurora borealis phenomenon.
Bodies in free fall or even bodies that fall accelerated by gravity, but suffer the action of air resistance.
See too:Astrophysics — the branch of Astronomy dedicated to the study of the Universe through applications of the laws of Physics and Chemistry
Classic Mechanics in Enem
Among all the areas of Physics, Classical Mechanics is the one that is present in the greatest amount in the Enem questions, so it is of great importance that you are able to:
understand the meaning behind the Kinematics equations, being able to relate them to real situations, as well as their graphs;
identify and classify progressive, regressive, accelerated and uniform movements;
understand the concept of reference and understand what relative movements are;
knowing how to apply Newton's three laws in the most different contexts;
understand the concept of mechanical, kinetic and potential energy and know how to operate with these quantities;
make collision calculations using momentum as well as conservation of mechanical energy;
know and understand the functioning of Kepler's laws and their relationship with the law of universal gravitation;
understand how static equilibrium conditions should be applied to bodies whose dimensions cannot be neglected;
understand the causes and effects of particle movements and know how to describe them in the form of equations.
What are the main areas of study in Mechanics?
The Mechanics It is one of the great areas of Physics. It is commonly divided into:
Classic Mechanics: a branch of Mechanics that studies the movements of bodies on Earth and immersed in fluids below the speed of light and the causes of these movements. It relates to the knowledge of the area that is applicable to macroscopic situations.
Quantum Mechanics: a branch of mechanics that studies the motion of minute particles, such as atoms and molecules.
Relativistic Mechanics: a branch of mechanics that studies the behavior of bodies moving at speeds close to the speed of light. It stems from the discoveries of physicist Albert Einstein.
Source
e-Física – Online Physics Teaching; USP – University of São Paulo. mechanics. Available in: http://efisica2.if.usp.br/course/index.php? categoryid=132.
By Rafael Helerbrock
Physics teacher
Would you like to reference this text in a school or academic work? Look:
HELERBROCK, Rafael. "Classical Mechanics"; Brazil School. Available in: https://brasilescola.uol.com.br/fisica/mecanica-classica.htm. Accessed on August 22, 2023.
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