Umm the one fired from the gun wtf?
If the bullet from the gun does not hit first by a huge margin, than your gun sucks.
If the bullet from the gun does not hit first by a huge margin, than your gun sucks.
The real question is what good comes from this?
[edit]
ohhh ok I FINALLY understand WTF was going on, and my answer is, I don't care Alex for $500?
[edit]
ohhh ok I FINALLY understand WTF was going on, and my answer is, I don't care Alex for $500?
TankGuys
Golden Member
- Jun 3, 2005
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The thing is, a lot of physics problems seem like "common sense" but are not.
This problem is a good example; people want to beleive the fired bullet will hit later since it's going faster/farther! However, it's only going faster in one axis, the fact is, both hit the ground at the same time.
That's really weird for non-physics people to grasp the differentiation between axes. It's the same reason why non math people have trouble with the .9999999999 = 1 thing. It all just depends on your background and where your education lies.
Kelemvor
Lifer
- May 23, 2002
- 16,928
- 8
- 81
Think of it this way. Any object in motion has a vertical and horizontal (we'll leave out the 3rd dimension since it doesn't apply to this problem). (leaving out air resistance, earth curvature, etc)
When the bullet is DROPped, it has a horizontal velocity of 0 and a vertical velocity of 0 which decreases by 9.8m/s^2
When the bullet is fired, it has a horizontal velocity of a big number depending on the gun and bullet, but the vertical velocity is also 0 and decreases by 9.8m/s^2.
While the fired bullet is moving faster sideways, movement sideways doesn't affect movement vertically. The vertical movement is only affected by gravity. So since they both start at the same height off the ground, and they both fall at a rate of 9.8m/s^2, they would both hit the ground at the same time. The dropped bullet would be at your feet and the fired one would be a hundred yars away.... but they'd hit the ground at the same time.
When the bullet is DROPped, it has a horizontal velocity of 0 and a vertical velocity of 0 which decreases by 9.8m/s^2
When the bullet is fired, it has a horizontal velocity of a big number depending on the gun and bullet, but the vertical velocity is also 0 and decreases by 9.8m/s^2.
While the fired bullet is moving faster sideways, movement sideways doesn't affect movement vertically. The vertical movement is only affected by gravity. So since they both start at the same height off the ground, and they both fall at a rate of 9.8m/s^2, they would both hit the ground at the same time. The dropped bullet would be at your feet and the fired one would be a hundred yars away.... but they'd hit the ground at the same time.
The fired bullet will always take longer. If you want to try & ignore the curvature of the Earth and have a flat surface to fire against, thoughout the length that the fired bullet will travel - at the end of this flat surface, the ground is slightly further away from the center of the Earth, causing the force of gravity to be ever so slightly weaker. Plus the force of gravity would be working at an angle against the fired bullet, so part of the gravitational force will be slowing the bullet down instead of pulling towards the earth.
The dropped bullet hits first.
The dropped bullet hits first.
Cerpin Taxt
Lifer
- Feb 23, 2005
- 11,940
- 542
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No, because it's not a question of force; it's a question of time. Yes, the fired bullet will impact the ground with greater force, but both bullets will fall VERTICALLY at the same rate. The immense force with which the fired bullet will impact the ground was HORIZONTALLY directed, and as such will not affect the VERTICAL acceleration.
A different question more along your line of thinking might be, if I was standing in a field and fired a bullet straight up into the air and it came straight back down to hit the gorund, at which point is the bullet going faster: the moment it exits the pistol's muzzle, or the moment it hits the ground?
-Garth
Ok, here it is.
You drop a bullet from 4 feet up. It falls straight down, takes 0.4988 seconds to hit (link)
You fire a bullet from 4 feet up. Typical round at 3,000 feet/second. At the end of .4988 seconds when the other bullet hit the ground, the bullet fired from the rifle has travelled 1496.4 feet in the horizontal direction. Due to the curvature of the Earth, the Earth's surface drops 1 foot every 6499.23 feet.
Therefore, at the time that the dropped bullet hits the ground, the rifle bullet will be 1496.4 feet away and will NOT have hit the ground yet, since it must fall another 0.23 feet, which is about 2.76 inches.
So there you have it. When the dropped bullet hits the ground, the fired bullet will still have 2.76 inches left to fall, due to the horizontal distance it covered and the curvature of the Earth.
You drop a bullet from 4 feet up. It falls straight down, takes 0.4988 seconds to hit (link)
You fire a bullet from 4 feet up. Typical round at 3,000 feet/second. At the end of .4988 seconds when the other bullet hit the ground, the bullet fired from the rifle has travelled 1496.4 feet in the horizontal direction. Due to the curvature of the Earth, the Earth's surface drops 1 foot every 6499.23 feet.
Therefore, at the time that the dropped bullet hits the ground, the rifle bullet will be 1496.4 feet away and will NOT have hit the ground yet, since it must fall another 0.23 feet, which is about 2.76 inches.
So there you have it. When the dropped bullet hits the ground, the fired bullet will still have 2.76 inches left to fall, due to the horizontal distance it covered and the curvature of the Earth.
Ok ok, I got another one.
When you drop a kitten, a puppy, and a baby off a 400 foot bridge into a raging river below, which one will surface first?
Assuming cats always land on their feet, dogs can utilize the "Doggie" paddle, and babies float.
Keep it strickly scientific plz.
When you drop a kitten, a puppy, and a baby off a 400 foot bridge into a raging river below, which one will surface first?
Assuming cats always land on their feet, dogs can utilize the "Doggie" paddle, and babies float.
Keep it strickly scientific plz.
TankGuys
Golden Member
- Jun 3, 2005
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I know why you would think that, and it seems to make sense, but it's not true.
2 reasons:
1.) Gravity always pulls straight towards the center of the earth. No matter how far that bullet goes, gravity is ALWAYS pulling it straight down.
2.) Even #1 weren't true, you're only talking about a 0.015 degree difference in angles by the end of the bullet flight, which is hardly enough to make much difference.
Good thinking though, I understand why it seems that way!
Oh my, there are a lot of stupid people that like to display it on these forums. Sometimes I forget that but then we have threads like this to remind me.
I think my favorite gem was:
Bullets fired horizontally can acheive escape velocity.
The runner up was that satelites don't fall out of space because there is no ground to fall into.
Always entertaining to read people, keep up the displays of stupidity.
I think my favorite gem was:
Bullets fired horizontally can acheive escape velocity.
The runner up was that satelites don't fall out of space because there is no ground to fall into.
Always entertaining to read people, keep up the displays of stupidity.
Cerpin Taxt
Lifer
- Feb 23, 2005
- 11,940
- 542
- 126
You need to parse the sentence more carefully. That statement says that the fired bullet is parallel to the ground, not the other bullet.
A more precise description would be that the bullet was fired a perpendicular 4' distance from a point on the earth's surface, and parallel to a tangential plane that intersects the earth at that point.
-Garth
The energy with which they impact the ground has nothing to do with it. The question asks WHEN they hit relative to each other. Since the horizontal and vertical components of force are independent, the vertical component of force (gravity) is constant for both, and both bullets have an initial vertical velocity of ZERO, they will hit the ground at the same time. This is covered in the first lecture of any physics class.
Of course this is neglecting air resistance which can cause lift or fall (force in the vertical direction) or can affect terminal velocity ballistics; effects of heat on ballistics; and curvature of the earth (which would cause a curved trajectory). Though for a bullet fired from a small height the curvature of the earth would be negligible.
Therefore, for bullets fired in a vacuum and small height = land @ same time.
For bullets fired in air, from a great height = unknown, depends on object's shape (aerodynamics) and path curvature.
Originally posted by: spacejamz
Just realized the bullet fired from the gun was travelling parallel to the ground and not the other bullet...
so if both bullets are moving vertically from 4' high, one dropped and one fired, which one would hit the ground first?
The same time. (Actually, that's a misconception. The dropped one would due to the curvature of the earth. But in a physics world, we don't have curvature. Or terrain. Or an atmosphere.)
This is assuming the bullet maintains it's speed, which it will not.
Applying the Physicist's favorite conditions (vacuum, infinitely flat surface, constant gravity, etc) they would hit at the same time.
Real world, the dropped bullet would hit first.
Kyteland
Diamond Member
- Dec 30, 2002
- 5,747
- 1
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That's only true if you ignore a lot of things, like the curvature of the earth. The question didn't state "There are two point sources on a frictionless plane, one dropped and one fired from 4 feet."Originally posted by: TankGuys
The thing is, a lot of physics problems seem like "common sense" but are not.
This problem is a good example; people want to beleive the fired bullet will hit later since it's going faster/farther! However, it's only going faster in one axis, the fact is, both hit the ground at the same time.
That's really weird for non-physics people to grasp the differentiation between axes. It's the same reason why non math people have trouble with the .9999999999 = 1 thing. It all just depends on your background and where your education lies.
So for whom is Newton spinning?
Originally posted by: RaynorWolfcastle
Originally posted by: Kyteland
The dropped one. Since the earth is a sphere, and not flat, the fired bullet will actually have farther to fall than the dropped one.
Note that this assumes that it is fired in a vacuum.
LOL, you want to ignore air resistance and the fact that terrain isn't flat but you want to take into account the fact that the Earth's surface is curved?
You must be a mathematician or a physicist
You can't shoot a firearm in a vacuum!!!!!!
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