Bullet

[MarkyP05]

If i were to be travelling on a train at the speed of a bullet and fired a single bullet out of the front of the train what would happen?

[Hippy]

The bullet would leave the muzzle of the gun at the same speed as it would normally (that is the same as if you were not on the train) plus the speed of the train. Just like any othe projectile it would travel in a sraight line for some distance, gradually slow down due to air resistance, and then gravity would become a more increasing force compared with the momentum of the bullet and it would fall to earth, provided it did not hit an obstacle on its way.

Now the train in the meantime would travelling in the same direction as the bullet, but unable to catch it up in the initial part of its trajectory. However, when the bullet's speed decayed and it fell to earth the train would now be much faster and it would catch it up, probably after the bullet had stopped moving and was lying on the ground. The disatnce travelled during the fast part of the bullet's trajectory is unlikey to be "made up" by the train, so there is no risk of firing forward and shooting yourself.

[tigga]

you would get arrested !.

[Greeno]

Errr gravity would affect it straight away. If you were to fire a gun on a flat plane i.e parallel to the ground and dropped a bullet from the same height they would hit the ground at exactly the same time. Horizontal and vertical forces are not related.

[Hippy]

Greno, thanks for that clarification. on re-reading my piece I can see how some people might think I was saying that gravity only acted at certain times and horizontal momentum at others or that maybe gravity increased as momentum decreased. What I said here was "... gravity would become a more increasing force compared with the momentum of the bullet ..." and I was expressing this from the bullet's point of view to describe the decaying arc trajectory. The gravity force remains constant while the momentum changes, so as the momentum reduces then gravity has a more noticeable effect on the shape of the arc. It hasn't increased, the other has reduced. Note my words "... compared with ..."

[Gef]

But, greeno, the bullets would not land in the same place.

[mastadon]

'place' has nothing to do with it