Show marly all Rela relative tiye what will happen to a bullo bullet tired fired directly to the rear from an airplane traveling with the same velocity as 33 the bullet this Is a question frequently asked and Is apparently of 0 increasing interest due to the part the airplane played in the last war and the ensuing public attention the answer is simply that the bullet will with a certain amount of irregularity due to its spin drop vertically to the ground from the point at which it leaves the muzzle ot of the gun in other words the plane runs oft off and leaves the bullet I 1 sounds impossible but its true the first thing which must be made clear says dr C S cummings supervisor of ballistics standardization at remington arms company Is that there is no such thing as motion by itself motion must always be relative to some other object we are so used to using the earth as the object relative to which we consider all motion to take place that we usually lose sight of the tact fact that other reference points may be adopted in this case probably the c contusion 0 n f u 5 10 11 which seems to exist concerning the bullet plane problem is due u e almost a 1 m 0 s t entirely e n r e to t 0 this t h I 1 s failure falln n lei f ayi r e to t 0 be b e specific s p e t as a s to t 0 the points of reference concerned As in many other instances a proper phrasing of the q question almost supplies me answer instead of phrasing the question as we did originally it should be asked as follows what Is the motion relative to the earth of a bullet which is fired in a rearward direction from a plane whose forward velocity relative to the earth Is equal to the velocity with which the bullet leaves the gun to be specific let us imagine that we are in a plane traveling feet per second due north the bullet is one which when fired will leave the gun tit at a speed ol of feet per second relative to the gun picture now the situation just before the shot Is tired fired the plane gun and gunner are all moving due north at the speed of feet per second relative to the earth the gunner pulls the trigger the bullet starts to move down the gun barrel that is changes its position relative to the gun since the gun is presumed fixed relative to the plane the bullet is not moving north quite as rapidly now as the plane and gun by the th e time the bullet reaches the muzzle of the gun it is traveling with its full velocity of feet per second away from the gun in a direction due south relative to an observer on the ground the velocity of the bullet Is zero hence the bullet will drop vertically to the ground from the plane on the other hand continues nr dr cummings if the bullet were fired from the nose of the plane it would mo move ve 1600 feet per second due north relative to the plane since the gun Is already traveling feet per second due north and the bullet leaves the gun gin at SOO ago feet per second relative to the he gun ua it if we assume that the air is stationary relative to the ground ie no wind then the above discussion cuss on is equally applicable to the motion of the bullet relative to the air in other words depending upon the direction in which the bullet is fired it will have a velocity ity of from zero to 1600 feet per second relative to the air thus very much complicating the problem of trajectories jec tories of bullets fired from rapidly moving aircraft |