Earphone definition, a sound receiver that fits in or over the ear, as of a radio or telephone. See more.
Answer Wiki. If a rocket went straight up, it would either continue in that direction and leave Earth, or it would fall back down, depending on its velocity. Most rockets intend to enter orbit, which is an elliptical trajectory, and it's much more efficient to arc into this trajectory than to go straight up and then accelerate laterally.
The first rockets. Everything on Earth â including us â is held down by the force of gravity. Without gravity, we would all float off into space. It is said that Isaac Newton discovered gravity when an apple fell on his head. In order to reach space, we use a rocket-powered launcher to overcome the pull of Earthâs gravity.