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.
Most of this weight is fuel, such as liquid hydrogen and liquid oxygen. Rockets need so much fuel in order to overcome Earthâs gravity. Only when they reach a speed of 28 000 km/h are they travelling fast enough to enter orbit.Most rockets are made up of two or three stages.When a stage has used up all of its fuel, it is separated to get rid of the dead weight.ockets need so much fuel in order to overcome Earthâs gravity. Only when they reach a speed of 28 000 km/h are they travelling fast enough to enter orbit.