Home Page General Articles Genesis Science Mission
Scripture Categories Genesis Science Mission Online Store

Creation Links

Anomalies Creation Science Talk Blog
Genesis Science Mission You Tube Channel

An Introduction Classical Mechanics


History of Classical Mechanics

Basic concepts of Classical Mechanics

Force and Motion

Motion in Gravity.

Limitations of Classical Mechanics

Applications of Classical Mechanics

Simple Machines

Complex Machines

       

Mechanics: The branch of physics dealing with the behavior of physical objects when they are subjected to forces or displacements.

Classical Mechanics: The field of mechanics that deals the physical laws that describe the motion of bodies under the action of a system of forces at every day sizes and velocities.


Limitations

Classical mechanics is not with out its limits because it is  limited in the sizes and speeds at which it is applicable. The is because when the size of the objects gets extremely small quantum mechanics comes into play but on the macroscopic level quantum mechanics produces essentially the same results as classical mechanics. Further more when the speed of the objects gets extremely fast relativistic mechanics comes into play while at the speed experienced in every day life relativistic mechanics produces essentially the same results as classical mechanics. Now at larger scales of size and distance celestial mechanics come into play but this is actually just an expansion of the principles of classical mechanics to larger scales.


History

Classical Mechanics has an ancient history with the science going back at least to ancient Greece with Greek philosophers like Aristotle. In practice many of the  principles of classical mechanics go back even further even if they were not yet formulated. Classical Mechanics became a full fledged empirical science starting with Galileo and then grew into the beginnings of physics as it is known today with men like Isaac Newton.


Basic concepts

Linear force

F = am
F  = force
a  = acceleration
m=mass

Circular motion

Moment of Inertia = I
I = m r2
m = mass
r = radius

Angular velocity = w
w = v / r
r = radius
v = linear velocity

Angular acceleration = a
a = a / r
r = radius
a = linear acceleration

Torque = t
 t = I a
I = moment of inertia
a = Angular acceleration

Gravity


F = Gravitational Force
G = Gravitational Constant
M
1 & M2 = gravitating masses

The Gravitational Force is always negative because its vector always points towards the center mass of the other body.

Force and Motion

The affect that a force has on the motion of an object not only depend on the size of the force and the mass but also on how it is applied to the object.

A force applied to the center of mass results only in linear motion

A force applied a little off the center of mass results in linear motion and a slow rotation.

A force applied more off the center of mass results in linear motion and a faster rotation.


  A force applied at the edge  of a mass results in linear motion and a still faster rotation.

A force applied a little off the center of mass on the opposite side results  in linear motion and a slow rotation in the opposite direction.

A force applied more off the center of mass on the opposite side results in linear motion and a faster rotation in the opposite direction.
 

A force applied at the edge  of a mass on the opposite side results in linear motion and a still faster rotation in the opposite direction


Motion in Gravity

Classically gravity is the universal force of attraction between objects with mass however General relativity shows gravity to be a result of a warping of space around those objects.

G = Gravitational Constant = 6.67300 10-11 m3 kg-1 s-2 

M1 = Mass of object #1.

M2 = Mass of object #2.

R = Distance between the centers of mass of the two masses.

F = Force of gravity

 

G = Gravitational Constant = 6.67300 10-11 m3 kg-1 s-2 

Me = Mass of the Earth = 5.9742 1024 kg 

M = Mass of object

R = Distance to the Earth’s center.

F = Force of gravity

g = Acceleration do to gravity.

A pumpkin chucking air cannon is a good example to illustrate this principle.
It shoots an object on a ballistic path that is perfect for this illustration.

If you fire your pumpkin chucking air cannon horizontally then the more power you put behind the shot the further the pumpkin goes.

If you raise the angle at which you fire your pumpkin chucking air cannon then the pumpkin goes further up to an angle of 45 degrees. When the angle goes above 45 degrees it decreases until it reaches zero at 90 degrees, however they do go progressively higher reaching a peek at 90 degrees.

If you fire your pumpkin chucking air cannon at a constant angle then the more power you put behind the shot the further the pumpkin goes.

On earth this  only works over short distances. The above model assumes a flat surface but the Earth is round as a result the Earth’s surface actually curves away from an object as it moves horizontally. To illustrate this on a larger scale requires pulling out a supper pumpkin chucking air cannon.

As a result as a pumpkin goes further it drops further than it would on a flat surface but at slow speeds this affect is small in fact so small that can be ignored. However as the pumpkin goes faster the effect becomes more pronounced. As the pumpkin goes even faster the effect becomes even more pronounced. Increasing the  pumpkin's speed even more the pumpkin’s path actually starts curve with the Earth’s surface eventually reaching the point where its path curves so munch that it reaches the other side of the Earth. Increasing the pumpkin’s speed just a little more and its path curves to the point where it misses the Earth surface entirely resulting in a complete orbit. This affect form the basic principle for satellites orbiting around the Earth and also forms the bases of celestial mechanics.
In one way the key to flying really is throwing yourself at the ground in such a way that you miss it. It just takes a speed of about 4.5 miles a second to do it around the Earth.


Simple Machines

Simple machines are mechanical devices which change the direction and or magnitude of a force and they are generally the simplest mechanisms for providing a mechanical advantage  Mechanical advantage is referred to as leverage. The term “Simple Machines” is also used to refer to the 6 classical simple machines which were defined by Renaissance scientists.

6 classical simple machines which were defined by Renaissance scientists.

Lever

Wheel and axle

Pulley

Inclined plane

Wedge

Screw

In the ideal simple machine the energy output exactly equals energy input.

Ein = energy input

Eout = energy output

Eout =  Ein

This principle is based on the principle of conservation of energy. (1st Law of Thermodynamics) Now it needs to be noted the real world is seldom ideal and in the real simple machines a small amount of the energy will be lost to friction. Energy can also be lost in a simple machine by material imperfections in the material the machine is made of.


Complex Machines

Complex Machine: Any system consisting of simple machines that work together as one machine.

A complex machine can be as simple as a pare of scissors or as complex as a Space Shuttle however scissors are a good example of a complex machine. A pear of scissors consist of: aA wheel and axle, and two levers and two wedges.


Applications of Classical Mechanics

Classical mechanics has virtually unlimited applications being particularly useful at the scales of size and speed of everyday life since those were the scales it was developed on.
Every aspect of human life is affected by the application of force in one manner or another. Forces like gravity and those of impacts are all around us and most of us are victims of them at some point in our lives. Our own bodies uses them to do work including the use of simple machines like levers such a our arms and legs

Conclusion

Classical Mechanics is the foundation of physics because it is where physics had it start and where its main participles were laid down. Classical Mechanics works fine within our every day experience but reaches its limits when dealing with the vary fast the vary small.


 

Sponsor a page

at $1 a month

$11 for a year

Support this website  with a $1 gift.

 
 

Visit our

Online Store

Gifts of other amounts

Click Here

 

Custom Search