You found a sample of igneous rock which is 875% Argon and % PotassiumHow many half-have passed? How old is the igneous rock?

magnified images possible images can be real = projected onto a screen

the motion of a pendulum is a classic example of mechanical energy conservation. a pendulum consists of a mass (known as a bob ) attached by a string to a pivot point. as the pendulum moves it sweeps out a circular arc, moving back and forth in a periodic fashion.

answer(20) psi;

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.