...with a colleague - he says that a bullet shot straight up in the air lands at the same speed at which it is fired - i say that this is not the case - £5 rides on this - anyone help?

bollocks (to the fella who says it is not the case)

U won the £5, but do u know why?

if that was done someplace where there is no air resistance then yes your friend is right, but with air resistance the bullet will land slower... still fast enough to plow strait through someone head.

You're both sort of right. Under ideal circumstances (meaning no air) a projectile that is fired strait up will land with the same speed it had when initially launched. If you fired a bullet straight up on the moon, for example, it would fall back to the lunar surface with the same velocity as when it was initially fired. Here on earth, however, air resistance will cause the bullet to slow down significantly as it falls back to the ground.

Slower, tumbling, but lethal. Here's a related thread (http://www.sciforums.com/showthread.php?t=33590). In Lebanon, I saw/heard various rounds coming down. The signature sideways impacts typically penetrated car sheet metal, cratered concrete, sank an inch into asphalt, and occasionally killed people. Sounds like ttttthhhhhhht-WHACK. It's adviseable to go inside when you hear a lot of this.

;) the angry mobs should celebrate more with their ak-47

bollocks (to the fella who says it is not the case)

bunty, as you are wrong, and so sure of your answer, care to tell us why you think this way? Or do you live on a planet with no atmosphere?

Guys guys guys, he won the £5 like I said. The bullet was fired through air for Gods sake. Read again.

:fires celebratory volley:

The whole reason a bullet comes back in the first place is because it wasn't traveling upwards fast enough to travel back downwards slower right?

The bullet comes back because it is too slow to escape the gravitational field. It travels back even slower.

The German V-2 reached 80 kms altitude after wich it reached Mach5 during the free fall, wich meant you heard the explosion on the ground first and the sound of the incoming missile a few seconds afterwards!

However the V-2 had a much larger mass to surface ratio than a bullet and it could build up speed falling from great heigts with low airdrag.

Doesn't matter what size or shape the object is. It will always reach a slower speed than that which it was set off at

No it won't, it will only slow if friction is involved, look up inertia.

The German V-2 reached 80 kms altitude after wich it reached Mach5 during the free fall, wich meant you heard the explosion on the ground first and the sound of the incoming missile a few seconds afterwards!

However the V-2 had a much larger mass to surface ratio than a bullet and it could build up speed falling from great heigts with low airdrag.This only works for ballistic projectiles. If the projectile is powered – like a rocket – then it won't necessarily come down at the same velocity it went up.

No it won't, it will only slow if friction is involved, look up inertia.

For Gods sake, friction is involved!!! I know what inertia is. What are u trying to say?

The bullet comes back because it is too slow to escape the gravitational field. It travels back even slower.

woops, I meant in a vacuum.

What Saith said. If there is no friction mass will retain momentum FOREVER.

But there is friction Wellcookedfetus! Why are u trying to argue for the sake of arguing?

In a real-world situation, the bullet will come down slower than it went up, due to air resistance. In a vacuum, the speed would be equal at equal heights on the way up and on the way down.

How many people are going to repeat the same thing?! The guy only wants to know what would would be the speed of the V2 rocket if it were to come down to earth. Forget about hitting golf balls on the moon!!!

it wouldnt even without air resistance. Remember the corialis effect.

The bullet goes straight up until it runs out of velocity. It then falls at terminal velocity minus sir resistance. Thus, whether it falls faster or slower will depend on the round you're firing.

Actually pondering this perhaps you should analyse:

A bullet is a projectile which is fired to create force that is enough to generate both the velocity at which the bullet travels, and force enough to beat gravity. However gravity and atmospheric friction cause the bullet to slow, then stop and then with gravity's aid fall to the ground.

Gravity will accelerate the bullet back to the ground at a constant without regard to mass. As the bullet falls to the ground it again negotiates the atmospheric friction.

There are also the extreme aspects to the case, did the bullet alter in shape from its innitial launch, does it shape have equally distributed weight or more at one end (This would make a difference when the Velocity going up, meets gravity pulling down only due to the higher weight attempting to be earthbound first at this zero'd sweet point.)

It suggests that down would be slower because of the aspects of extreme cases.

Other experiments along the lines of constant velocity were performed by Galileo, however I would note that Galileo was shunned by Religion and classed a heretic, apparently they probably think the bullet goes straight up. j/k

It suggests that down would be slower because of the aspects of extreme cases.

Don't worry, the bullet ALWAYS comes down slower in this situation.

What is the terminal velocity of a typical bullet?

Depends on what the typical launch speed is. Can u provide us with that?

...with a colleague - he says that a bullet shot straight up in the air lands at the same speed at which it is fired - i say that this is not the case - £5 rides on this - anyone help?
I guess youd have to measure the speed of the bullet being fired,Im guesing its something like 2000-3000 feet/sec or so,depending on a gun,obviously.
now bulet or any other object faling back down to earth will reach about 200 mph velocity,
you do the math. ;)

Some guns will go below 800 feet/sec. Pick out three cartridges and guns. Both have an impact on the muzzle velocity.

Muzzle velocity is irrelevant to terminal velocity, which depends only(!) on the bullet's size, shape, mass, and orientation. Orientation is easy - a spinning bullet will keep a constant orientation, so if fired straight up it will fall point-up.

Straight Dope (http://www.straightdope.com/classics/a950414b.html) cites a military ordnance test which found that the terminal velocity of a .30 cal 0.021 pound (10g) bullet was about 300 feet per second (90 m/s).

Bottom line - a bullet fired straight up will fall at much slower than muzzle velocity.

Saith: Is it the terminal velocity u want or just the velocity as it lands? I am sure there are some muzzle velocities whereby the bullets do not reach terminal velocity.

Isn't the bullet going to land at terminal velocity? I think most guns, including handguns, go faster than 600 mph.

Well I worked out that the bulllet will then land at a speed of about 225 m/s. Now in a certain forum that I cannot name ( :D ) someone suggested the terminal velocity can be anywhere between 100-400 m/s so it will not always reach terminal velocity.

Actually the terminal velocity of a human is more like 120MPH this is about 54 m/s while that of a bullet seems to be anywhere from 100~400m/s depnending on the size and mass of the slug. (Note the high end is for a 14" Naval gun!)

U have to remember that these objects are designed for high speed flight

Here's the link: bullet terminal velocity (http://www.*************.com/showthread.php?s=&threadid=14560)

What size bullet was that, John?

Here is the link from the link:
Bullets in the Sky (http://www.loadammo.com/Topics/March01.htm)

And a similar link:
rec.guns.faq (http://www.logicsouth.com/~lcoble/dir5/xd.txt)

No, I just wanted to find out what what speed it would be as it hits the ground with no air resistance (assuming a muzzle velocity of 810 km/hr. 'Work out' was the wrong word there, I was just changing the units!

So the moral of the story is that a bullet will only reach terminal velocity upon freefall if its muzzle velocity exceeds that number.

I'd bet $5 that for small arms the muzzle velocity always exceeds terminal velocity.

Your on! Nah, Im only messing, I would imagine the same thing :)

Fetus, it will keep going for an incredible amount of time, but not forever. If Stephen Hawking can figure out how black holes die, then I have some trouble believing that the momentum of an object in a perfect vacuum with no gravity is eternal.

hate to burst your bubble but any objects pulled purely by the earth gravity cannot fall faster than 32feetpersecond so unless you have a magnet or shoot it downwards thats as fast as it will go

You are getting mixed up between velocity and acceleration Vslayer! If everything were to fall at that speed then most people would survive a fall from a plane at 30,000 ft!

...with a colleague - he says that a bullet shot straight up in the air lands at the same speed at which it is fired - i say that this is not the case - £5 rides on this - anyone help?

No. Depending on the round & powder load, a bullet might exit the barrel at say...2000 ft. per second (for a higher velocity round). It will travel up & away from the Earth until it stops & falls back to the Earth. It will then fall back to the Earth At 32 Feet Per Second, Per Second, minus the restriction caused by the the air resistance which increases as the bullet gets nearer the surface of the earth (the air is thicker/more resistant at the Earth's surface).

If a bullet were to be fired from a planet, with no atmosphere, the result would be the same, except that the planet or planetoid would have to be quite smaller, thus incapable of holding an atmosphere around it. So most likely, the bullet would (well might)acheive Escape Velocity..........

But there is friction Wellcookedfetus! Why are u trying to argue for the sake of arguing?
hi john, welcome to the world of wellcookedfetus.

he's an idiot, who thinks he knows everything, is never wrong, and always gets the last word.

my advice, put him on ignore

I resmble that remark.

wouldnt it acutally hit the ground faster because of gravity.
Because on the way up it has air resis and gravity slowing it and on the way down it has gravity helping it but not air resis