science question?

Question

what common techology doesnt efficiently convert energy? explain

Answer 1

One of the least efficient energy conversions involves airplanes at takeoff, especially at the lower speed part. This also applies to rocket liftoffs and initial boat accelerations. You have a powerful engine accelerating large amounts of some massive medium (air, rocket exhaust, water) to high speed to produce thrust. But in the early stage, power delivered to the vehicle (thrust times vehicle velocity) is low, thus kinetic energy accumulation is far less than energy expended. All these processes become more efficient in the mechanical sense as the vehicle speeds up, but any practical way to have initial velocity buildup occur with some form of power other than reaction (e.g., a tractor device) would use far less fuel.

Answer 2

A megaphone, because sound comes in, and sound comes out. It is amplified, but it is not converted, so it is still sound.