drop of a bullet vertically vs. horizontally

Discussion in 'The Club House' started by thepit56, Jan 16, 2008.

  1. thepit56

    thepit56 New Member

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    My physics teacher told us that if you drop a bullet and fire a bullet horizontally that they will fall at the same rate and hit the ground at the same time. somehow I don't believe this. if this is true how can a bullet travel hundreds of yards? can anyone explain this to me.
     
  2. Righteous

    Righteous New Member

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    I dont believe it either but how hell ya gonna prove it
     

  3. Tanker60A3

    Tanker60A3 New Member

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    Gravity

    Gravity is pulling both bullets down at the same rate (assuming both bullets are the same). Both bullets should hit the ground at the same time, if the ground is level, and if the fired bullet was fired parallel to the ground. The difference in impact points is due to the explosive energy from the gun powder driving the fired bullet forward as it falls.
     
  4. deadin

    deadin New Member

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    A bullet begins to fall the instant it leaves the muzzle. That's why the line of bore is higher than the line of sight. Where they cross is what the gun is sighted in for. However there are other things to consider. The main one is barrel rise due to recoil (especially in a handgun). But these are interior ballistics that effect things before the bullet exits the bore. Once its out, gravity takes over and is boss.
     
  5. cpttango30

    cpttango30 New Member

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    If both bullets are exactly the same. Say a .224" 50gr Hornady V-max. If you shoot a bullet and drop it at the same time yes they will hit the ground at the same time. Gravity is a constant and never changes on earth.
     
  6. MarkoPo

    MarkoPo New Member

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    This would only prove true in a vacuum. Same as droping a lead weight and a feather. In a vacuum both will hit bottom at the same time.
     
    Last edited: Jan 16, 2008
  7. Flint Rock

    Flint Rock New Member

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    Gravity

    I can't think of any bearing that a vacuum would have on the rate of fall, unless by vacuum you just mean a lack unequal external forces acting on the bullets. Gravity is the determining factor here.
     
  8. jeepejeep

    jeepejeep New Member

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    Doesn't need to be a vacuum. Gravity pulls the same no matter what just as others have said here.
     
  9. jeepejeep

    jeepejeep New Member

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    Correct except line of bore is BELOW line of sight. Think about it: sights or scope on a gun (line of sight). Above or below the barrel?
     
  10. Duck

    Duck New Member

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    Yes, you do need the vacuum. Air creates resistance that takes a greater effect on a lighter object. Don't believe me? Drop a piece of paper and a rock at the same time. The air resistance restricts the paper's fall. In a vacuum, there is no air so the resistance isn't there.

    Also, a bullet actually arcs upwards as it leaves the muzzle. That bullet would have a further distance to fall, so would probably hit the ground last.
     
    Last edited: Jan 17, 2008
  11. Flint Rock

    Flint Rock New Member

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    Gravity

    No, you don't need a vacuum. The air will act equally on both objects if both objects are equal in mass and weight, which they are since "they" are both identical bullets.
    You would only need a vacuum if the two dropped items are of equal weight, but of differing mass. A 55 grain balloon would fall as fast as a 55 grain bullet in a vacuum, but we didn't start out talking about balloons, bullets, and vacuums, only bullets.
    Equal mass, equal weight, equal fall rate regardless of lateral velocity. Unless there is a force to counter act gravity, everything falls.
    Gravity always wins, it may take a million years, but gravity wins.:)
     
  12. jeepejeep

    jeepejeep New Member

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    No Duck. The OP said the barrel is level. Bullets do not rise if the barrel is parallel to the ground. They actually start dropping as soon as they leave the barrel. If the bullets are the same weight they will hit the ground at the same time. It's physics. You are comparing paper and a rock totally different from two identicle objects.
     
  13. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

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    It is a very common misconception that bullets rise as they leave the barrel because of the advertising showing an arc trajectory. There is only an arc because the barrel is pointed upward in relation to the sighting device. The sights/scope must be misaligned to compensate for the drop. The bullet drops "relative to the bore", disregard the point of aim.
    Gravity is a constant 32.2 feet per second per second (F/S/S). If you shoot a bullet from a level bore at 32.2 feet above the level ground the bullet will be in the air for EXACTLY 1 second. Velocity does not matter. Weight/mass does not matter. Ballistic coefficient does not matter. A .45 ACP 230 gr FMJ at 830 fps will hit the ground at the same time as a 55 gr FMJ fired at 3200 FPS out of a 5.56 mm. The 5.56 mm will travel FARTHER in that one second but will be in the air for the EXACT same amount of time.
     
  14. jeepejeep

    jeepejeep New Member

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    Is that right? Interesting. I would think the heavier bullet would hit the ground first. The foward velocity does not matter but if both were held next to each other and dropped at the same time I'd think the .45 would hit the ground sooner.
     
  15. MarkoPo

    MarkoPo New Member

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    That logic doesn't work either. If I shoot a bullet out of a perfectly level barrel at 32.2 feet in the air it will travel in the air far longer then 1 second. Think of some of the 50 caliber rifles. Those rounds can travel miles before hitting the ground. The rifling of a bullet spins the bullet so fast leaving the barrel it will keep it going level longer. Now a 12 gauge slug might hit the ground in a second, but a high powered rifle will travel longer in the air.
     
  16. MarkoPo

    MarkoPo New Member

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    Ok I got to thinking about this more. So if this were true, I shoot a gun with a velocity of say 2500 FPS. I shoot it from a height of exactly 32.2 feet in the air and perfectly level. With no outside factors like rain or wind acting on it, it will strike the ground 2500 feet out and and exactly 1 second later? HMM...This could make sence but I would have to see it to believe it. I still think the rifling may effect the outcome of this test.
     
  17. robocop10mm

    robocop10mm Lifetime Supporting Member Lifetime Supporter

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    The rifling gives the bullet stability, not lift. The bullet fired at 2500 fps will not strike the ground 2500 feet away 1 second later. Air friction acts upon the bullet immediatley upon leaving the barrel so it begins to slow down. depending on the ballistic coefficient (how much the air friction effects it) it will hit the ground some where less than 2500 feet away.
    This whole concept runs counter to what the "traditional wisdom" has taught us. It can be a hard pill to swallow but true.
    Physics class in High School was never this interesting or thought provoking, was it? I had the good fortune of taking Physics for Criminal Justice Majors in college (2 semesters) and the professor used real world examples like this to spur learning. Then later I attended 160 hrs of Accident Investigation and Reconstruction. We used problems like this to understand the physics involved in motor vehicle crashes. Science is cool. Wish I had teachers in High School that understood how to make a topic fun.
     
  18. deadin

    deadin New Member

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    Here's an experiment for you. Take a bolt action rifle (You will see why I said a bolt action in a moment) , sight it in for, say, 300 yds. Sandbag it so it will not move, align the sights on the target 300 yds away. Then carefully, without disturbing the sight alignment, remove the bolt. When you squat down and peer thru the bore, you will find it pointed somewhat above the target. There are always two points that are exactly on where the sights point, One is when the bullet is on the way up, (this is because, as you said, the sights are above the bore) and the other is when the bullet is on the way down. I seem to remember that a 30/06 sighted in at 150 yds is also on at 50 yds. This phenomenon is called mid-range trajectory and is listed in most performance charts. It is the highest point a bullet attains on the way to the point of aim. Point blank means that the target is so close that mid-range trajectory doesn't come into the calculation. The time in flight is so small that the bullet doesn't have time to fall any appreciable amount.
     
  19. jeepejeep

    jeepejeep New Member

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    Yes the barrel might be pointed above the scope or sights but physically the line of sight is above the bore.
     
  20. deadin

    deadin New Member

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    Think outside the box. The term used was "line of bore" not just plain "bore".
    If you want to talk about the hole in the end of the barrel, yes, the sights are above that. However the "line of bore" is the projected line down the center of the bore from the breech to the muzzle and beyond, all the way out into the distance. The same thing with "line of sight". It's not just where the sights are on the barrel, it's all the way to the target when the sights are aligned on the target.