![]() Momentum is the measure used in physics to quantify the “impulse” the force exerted over a period of time IN ONE SPECIFIC DIRECTION. The kinetic energy of an arrow, by definition, is not a direct indicator of the penetration capability of the bow-arrow-broadhead combination. alone as a predictor of penetration capability also fails to take into consideration the mechanical advantage of the broadhead and the coefficient of resistance. includes such things as radial energy due to arrow flexion rotational energy due to arrow spin sonic energy due to vibration heat energy due to friction and potential energy (all other remaining energy). It is the TOTAL ENERGY of a body in motion. This use of kinetic energy reflects a misunderstanding of these basic principles of physics.īy definition, kinetic energy is the capacity to do work. With the advent of compound bows and overdraw setups, with their higher velocity capability, it has become common to see kinetic energy figures cited as a supposed measure of the penetration capability of a particular bow-arrow-broadhead combination. The kinetic energy (K.E.) of a moving body increases as the square of the velocity and directly as the mass whereas the momentum increases directly as both the velocity and/or mass increases. Kinetic Energy = Weight X Velocity Squared The equations for these two measurements are: Kinetic Energy Vs MomentumĪs a base point for a discussion of momentum and kinetic energy, one must understand that the laws of physics dictate that energy can never be manufactured or destroyed but only transformed or directed in its flow. ![]() The mechanical advantage equation dictates that the greater the length of a broadhead relative to the width, and the fewer the number of blades, the more efficiently it will be able to utilize the force applied to it. It does 100% more than the four blade, 150% more than the five blade and 200% more than the six blade broadhead. In example #2, a single blade head would be able to 50% more work than a three blade broadhead with the same applied force. 75″ high (a common dimension) the M.A.’s work out as follows: In a broadhead with a cutting edge length that is 2.25″ long and with each blade. would be 1.5, or one half that of the single blade. would be 2.0, ie: (3″ length/.5″ lift distance X 3 blades). If that same head has three blades, the M.A. In an equation, this would be expressed as:Īs stated above, a single blade broadhead 3″ long by 1″ wide has a mechanical advantage of 3.0. To determine the mechanical advantage of any broadhead with a straight taper to the cutting edge, divide the horizontal length of the cutting blade by 1/2 the width of the broadhead (or, more precisely, the distance from the central axis of the arrow to the highest point on the plane) multiplied by the number of blades. the more work a broadhead can do with the force available. What this means is that with an exerted force (effort) of 1 pound, a weight of 3 pounds can be lifted from the tip of the broadhead to the back edge of the broadhead. The mechanical advantage of the two planes combined would be 3.0 because the height would be doubled while the length remains the same. The mechanical advantage of an inclined plane is equal to the length of the plane divided by the height of the plane.Ī single blade broadhead, with a straight taper, 1″ wide by 3″ long can be viewed as 2 inclined planes, each of which has a mechanical advantage of 6.0 (3″ divided by 1/2″). The mechanical advantage (M.A.) of a “simple machine” is the ratio of the resistance to the effort. As such, all broadheads are no more than a series of inclined planes. In terms of physics, all broadheads are classed as “simple machines”. Much of the misuse originates from a lack of understanding of what, by definition, these terms mean and what it is they measure. All are used and often misused, in attempts to predict the terminal performance of various bow, arrow and broadhead combinations. Kinetic energy, momentum, mechanical advantage and coefficient of resistance are a part of the basic terminology of physics. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |