train moving at velocity "v" relative to earth My question is a basic one so patience would be appreciated =) Say we have a train moving at velocity "v" relative to the Earth. A man standing inside shoots a bullet at velocity "w" relative to the train's motion. The bullet should thus move at a speed of "v+w" relative to the Earth. I find this almost counter-intuitive. The speed the bullet attains is dependent only on the force exerted on it by the gun, regardless of how fast the gun is moving. It seems to me the bullet should retain its original speed "w". Although I am obviously wrong it would be helpful if someone could explain to me why. Thanks!