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.
Rockets work by accelerating gas to very high speeds inside and then letting the gas escape from the back of the rocket. Sir Isaac Newton discovered that an object can only be accelerated if a force is applied to it. He came up with a simple equation to describe this: