Armed Services Vocational Aptitude Battery (ASVAB) is an examination for military enlistment that includes ten different tests including mechanical comprehension tests. Mechanical Comprehension Test is quite different from your topics in high school that is why it is important that you choose your own study material in preparation for this exam.
In connection to this, this article will lead you to a comprehensive ASVAB Mechanical Comprehension Study Guide that would best fit your preparation needs for the military. The complex lessons of this topic are introduced in a way that you could easily understand.
FUNDAMENTALS OF MECHANICS
Mechanics is primarily defined as the description of forces and energies related to moving objects. It is a branch of physics that lets you describe and predict conditions of rest and movement of matter subjected to the action of forces. There are at least four basic components of mechanics—mass, velocity, acceleration, and force.
Mass is the measure of resistance to force or the total number of atoms in some materials. Velocity pertains to the speed and direction of moving objects. Acceleration, on the other hand, is a change of velocity on an object. However, an object moving at a constant velocity has no acceleration. Further, force is the energy or strength that is an attribute of movement or physical action. Thus, the force causes acceleration while a change of velocity is a manifestation of force to an object.
PRINCIPLES OF MECHANICS
In applied mechanics, there are at least six fundamental principles that you should remember:
- Newton’s First Law of Motion
The very well-known first law of motion states that an object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of the external force. This is also known as the Law of Inertia. It claims that unless a net force acts upon the object, it will always remain in a constant velocity. When the matter is left at rest, it means that it does not have velocity.
- Newton’s Second Law of Motion
This law of motion talks about what happens to a massive object when acted upon by an external force. It states that the force acting on an object is equal to the mass of that object times its acceleration. Thus,
F=ma, where F is the force, m is the mass, and a is the acceleration
When outside and a constant force acts on a body, it causes acceleration, thus changing its velocity at a constant rate. It accelerates based on the direction of the force which acted to it. On the other hand, if the object is already at a constant speed, the body might speed up, slow down, or change its direction depending on the intensity and the direction of the external force.
- Newton’s Third Law of Motion
This law emphasizes what happens to a body when it exerts a force on another body. It states that for every action, there is always an equal and opposite reaction. Forces usually occur in pairs, which means that a body cannot exert a force on another body without experiencing force itself.
These laws have been the foundation of many experiments throughout the years. They are also applied in many instances in everyday life. They are considered the basic principles of classical mechanics.
One concept that is applied to engineering mechanics is friction. Friction is usually defined as the retarding force that acts in contrast with motion when a body moves. It also pertains to the resistance of motion which scientists believe is a result of electromagnetic attraction between charged particles in two contacting surfaces.
Types of Friction
Friction has different types depending on where it has occurred:
Dry Friction or Coulomb Friction
This type of friction usually happens when two non-lubricated friction comes in contact and rubs with each other. When friction happens on this, one side may have an effect on its surface.
This friction happens when two fluids move at various velocities where the relative velocity on the layers causes frictional forces.
Also called friction drag, it is a component of the force which resists the motion of a solid body through a fluid.
ENERGY, WORK, POWER
Energy, work, and power are the three main terms which physics and mechanics often use. Work is done when a force applied to an object has moved the object. The formula for work is:
W= F x d; where W is for Work, F is for force, and d is for distance
The basic unit of work joule is represented by a capital letter J. This unit of measurement was derived from James Prescott Joule.
On the other hand, Energy is simply defined as the capacity to do work. The formula for potential energy is:
PE= mgh; where PE is for Potential Energy, m is of mass, g is for the gravitational field, and h is for height. Its unit of measurement is also in Joules.
Lastly, power is defined as the rate at which work is done. The formula for this is:
P= W/t; where P is for Power, W is to work, and it is to time
Its unit of measure is through watt which is represented by a capital letter W.
The principles of mechanics work with machines. Machines are used to reduce work and force while increasing the product. For instance, a simple machine uses an applied force to work against a single load force. The work done on the load is proportional to the work done with the applied force if the friction losses are ignored. However, the increase in the amount of the output force means the decrease in the distance moved by the load.
Further, a machine produces force and controls its motion. However, it cannot create energy.
Gears in simple machines are examples of mechanics. This has a wheel and axle that has teeth around it. They are often used with another set of gear to change the directions of forces. Its size determines its speed at which it rotates. This is often used to increase force or speed.
For more mechanical questions that you might find on the test, start training with us now. All the Mechanical Comprehension practice tests on our website are based on the previous ASVAB tests and simulated as close as possible to the actual test. To get 100% ready for your big day, take our free mechanical comprehension practice test as many times as possible.
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