Why is circular motion at constant speed not a natural state of motion?

Photons with the highest energy have the longest period

Does heating a metal wire increase or decrease its electrical resistance? why?

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector inside a tv tube. the electron strikes the screen after traveling 26 cm horizontally and 19 cm vertically upward with no horizontal acceleration. what is the constant vertical acceleration provided by the deflector? (the effects of gravity can be ignored.)