19. What form of potential energy occurs at Point C that allows the pole vaulter to lunge up into the air? Gravitational potential energy Chemical potential energy Elastic potential energy

The length of a vector arrow represents its magnitude and the point represents its direction true or false apex

Asample of silver (with work function ? = 4.52 ev) is exposed to an ultraviolet light source (? = 200 nm), which results in the ejection of photoelectrons. what changes will be observed if: silver is replaced with copper (? = 5.10 ev) more photoelectrons ejected no photoelectrons are emitted fewer photoelectrons ejected more energetic photoelectrons (on average) less energetic photoelectrons (on average)

Non renewable resources like petroleum eventually