A man is standing inside a train compartment. He then hits one side wall of the compartment with his hand (or you can assume he kicks the wall with his leg). Will the compartment begin to move? I don't think so. (If it happens, there will be no need of fuel.) I mentioned this incident as a backg...

When we are in an empty room with no one around, we don't hear any sound, but there are billions of atoms and molecules that are colliding at the same instant so, Why it happens that when two atoms or molecules collide with each other and produce no sound?

Could an object convert heat in the air around it to mechanical energy in order to accelerate itself? In other words, the craft would take in surrounding air composed of random-velocity molecules and then eject the gas back out in a more unified direction so that it accelerates in the opposite di...