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The Arrow


            While a bullet can be more easily thought of as a sphere, or a
        point particle, it is not as easy to imagine an arrow as either. An

        arrow is a flying stick, and as such it flys quite differently than
       
        does a bullet.

            When an arrow is released not only is it being act upon by

        gravity, making it a projectile, but also by air resistance, the force

        exerted by the bow, and an arrows tendency to spin. accoutning

        many of these forces and torques are the vanes of the arrow, or

        the fletching. They help to stabilize the flight of the arrow, much

        like wings on an aircraft.
           

























                                                                                                                                   



Indian_arrows
From http://www.by-the-sword.com/



                    While a bow is impressive in its versatility and power, it would be rendered nearly useless if it wasn't for the arrow. Again comparing to its modern day counterpart,
       
        the gun, the arrow is the "ammunition" of the bow. This projectile, while thought of analogously to the bullet, is rather different from bullet in its design. Remember, an

        arrow is fired from a large spring called a bow, therefore in the bow-arrow system, the elastic potential energy is transferred from the bow into the kinetic energy of the arrow.

        This is true for the most part. There are some dampening forces involved such as the vibrations that the bow undergoes after being fired. These are dissipated throughout the

        bow and usually are not harmful to the bow. However, when a bow is "dry fired", released with out an arrow, the energy that usually is imparted to the arrow is also

        still present to take place in those vibrations. This can be harmful for the bow.
                   

                    


Projectile Motion and Newton's First Law



          Definition:

            Projectile: a body that is projected by external force and continues in motion through its                 own inertia.

        Explanation:

            The concepts of Newton's First Law, and acceleration due to gravity both apply to                         projectile motion, and must be understood and used to complete these types of questions. If        
        an unbalanced force acts on an object, it will accelerate in the direction of the unbalanced                     force. If an object is given a certain initial velocity, and there are no unbalanced forces acting        
        on it, the object will continue along its original path in a straight line. With a projectile there is       
        the unbalanced force of gravity which acts only downward on the object. If air resistance is                 negligible, there is no force acting horizontally. So, the projectile will travel horizontally with 
        constant velocity and at the same time accelerate downward (Physics 24/7).




          
               Another factor that must be considered in an arrow is an arrows ability to bend to one side or another during the firing of the bow. This can be seen in slow motion videos

         taken of an arrow upon release. This produces an oscillation, or "wobble" in the flight of the arrow. This oscilation raquires energy and further removes it from the arrow.

         Another factor involved in this bending of the arrow is the spine of the arrow. This is a measurement that takes into account the thickness of the wall of the shaft of the arrow,

         and the diameter of the shaft. Also, many modern day arrows are hollow, raising the moment of inertia of the axis of the arrow helping to deny spin and retain energy

         ( Grundman, D. ).







                                                                                                                                                                                                                                                                                                                                       









Bibliography