I've been asking myself a question for quite some time :
- say that a bullet gets out of a gun at 900 km/h (I'm european, hence the metric system).
- say a train could go in a straight line at 900 km/h
- say you're at the back of that train, and you'd shoot a bullet backwards. The bullet exits your gun at 900km/h and flies away from the train at the same speed. However, what would happen for an earth observer?
You'll agree that if you shoot in an open field, the bullet will stay at the same altitude for several seconds before falling to the ground (with a field large enough). So from that train, same thing applies. So for the earth observer, the bullet will not have an horizontal speed, and will stay at the same altitude for several seconds before falling to the ground. So basically it'll float up in the air without falling. That'd be strange for the earth observer, right?
But the horizontal speed will decrease of course. So for the earth observer, the bullet will, for a few seconds, stay still at the same position, and then after several seconds will start to fall down a little bit, and will start to move towards the train, because its horizontal speed towards the train will decrease. Strange again!
OK last one: what would happen if the earth observer tried to catch the bullet with his bare hands? Nothing right? Just maybe a very hot bullet because of the explosion but it'd be basically as easy to catch as a stone floating up in the air? And don't tell me that the bullet will slow down due to air friction, because remember the bullet is not moving. Or very slowly.